What is the origin of symbols like '@' and '#'? + The Origin of Other Signs! (from Oxford Living Dictionaries)

@ ⇒ The '@' sign originated as a scribe's quick way of writing the Latin word ad, especially in lists of prices of commodities. It's usually just known as 'the at sign' or 'the at symbol': although it has acquired various nicknames in other languages, none of these has so far caught on in English.

# ⇒ The '#' sign has several names. The most common is probably hash. 

• In North American English, it's sometimes called the pound sign and used as a symbol for pounds weight: this can be confusing for British people for whom a pound sign is £.
• It's also known as the number sign in North American English, in contexts such as go to question #2. In a musical context, the symbol is known as a sharp. 
• The picturesque name octothorpe has also been introduced: it's said to have been invented by an employee of Bell Laboratories in the 1960s, in honour of the American athlete Jim Thorpe (with the octo-part deriving from the symbol's eight points).
• In the large form in which it appears on telephones it's sometimes called a square.
• Recently, the hash sign has acquired a new role. On social networking sites such as Twitter, it's attached to keywords or phrases so as to identify messages on a particular topic (e.g. #volcano; #Iceland). These keywords or phrases are known as hashtags.

💡 You may also be interested in:

1. Is there a name for the dot above the letters i and j? ⇒ The dot above the letters i and j has a name – do you know what it’s called?
2. What is the origin of the ampersand (&)? ⇒ The ampersand is the ‘&’ symbol that stands in place of ‘and’ – but where did it get its curious shape, and how long have people been using it?
3. What is the origin of the dollar sign ($)? ⇒ Have you ever wondered where the dollar ($) sign came from? Our video explains the origin, and it might be different to what you think.
4. What is the origin of the pound sign (£)? ⇒ Have you ever wondered where the pound (£) sign came from? Our video explains the origin, and it might be different to what you think.
5. What is the origin of the question mark? ⇒ Rather fittingly, the answer is somewhat clouded in myth and mystery… we ask some searching questions on the topic.
6. Is a question mark a full stop? ⇒ A question mark is used to indicate the end of a question. Which other functions does it have?
7. Is emoji a type of language? ⇒ Emojis are everywhere – but do they count as a language? We explore the issue.

🔗 Go to Questions about symbols.

💡 Or take a look at: What is the origin of the word 'quiz'?

💡 You may also be interested in: What is the origin of the word 'OK'?

💡 See other questions about the origins of words and phrases

🔗 See more from Language Questions at Oxford Dictionaries Explore

Why you really are as old as you think, by David Robson (from BBC Future)

Most people feel younger or older than they really are – and this 'subjective age' has a big effect on their physical and mental health.

As they get older, people with a younger subjective age are less likely to develop dementia and they even have a reduced risk of mortality (Credit: Javier Hirschfeld/Getty Images)

Imagine, for a moment, that you had no birth certificate and your age was simply based on the way you feel inside. How old would you say you are?

Like your height or shoe size, the number of years that have passed since you first entered the world is an unchangeable fact. But everyday experience suggests that we often don’t experience ageing the same way, with many people feeling older or younger than they really are.

Scientists are increasingly interested in this quality. They are finding that your ‘subjective age’ may be essential for understanding the reasons that some people appear to flourish as they age – while others fade. “The extent to which older adults feel much younger than they are may determine important daily or life decisions for what they will do next,” says Brian Nosek at the University of Virginia.

Its importance doesn’t end there. Various studies have even shown that your subjective age also can predict various important health outcomes, including your risk of death. In some very real ways, you really are ‘only as old as you feel’.

Given these enticing results, many researchers are now trying to unpick the many biological, psychological, and social factors that shape the individual experience of ageing – and how this knowledge might help us live longer, healthier lives.

This new understanding of the ageing process has been decades in the making. Some of the earliest studies charting the gap between felt and chronological age appeared in the 1970s and 1980s. That trickle of initial interest has now turned into a flood. A torrent of new studies during the last 10 years have explored the potential psychological and physiological consequences of this discrepancy.

One of the most intriguing strands of this research has explored the way subjective age interacts with our personality. It is now well accepted that people tend to mellow as they get older, becoming less extroverted and less open to new experiences – personality changes which are less pronounced in people who are younger at heart and accentuated in people with older subjective ages.

Interestingly, however, the people with younger subjective ages also became more conscientious and less neurotic – positive changes that come with normal ageing. So they still seem to gain the wisdom that comes with greater life experience. But it doesn’t come at the cost of the energy and exuberance of youth. It’s not as if having a lower subjective age leaves us frozen in a state of permanent immaturity.

Feeling younger than your years also seems to come with a lower risk of depression and greater mental wellbeing as we age. It also means better physical health, including your risk of dementia, and less of a chance that you will be hospitalised for illness.

Yannick Stephan at the University of Montpellier examined the data from three longitudinal studies which together tracked more than 17,000 middle-aged and elderly participants.

Most people felt about eight years younger than their actual chronological age. But some felt they had aged – and the consequences were serious. Feeling between 8 and 13 years older than your actual age resulted in an 18-25% greater risk of death over the study periods, and greater disease burden – even when you control for other demographic factors such as education, race or marital status.

There are many reasons why subjective age tells us so much about our health. It may be a direct result of those accompanying personality changes, with a lower subjective age meaning that you enjoy a greater range of activities (such as travelling or learning a new hobby) as you age. “Studies have found, for example, that subjective age is predictive of physical activity patterns,” Stephan says.

But the mechanism linking physical and mental wellbeing to subjective age almost certainly acts in both directions. If you feel depressed, forgetful, and physically vulnerable, you are likely to feel older. The result could be a vicious cycle, with psychological and physiological factors both contributing to a higher subjective age and worse health, which makes us feel even older and more vulnerable. (Continue reading)

🔗Go to FULL ARTICLE ⇒ The age you feel means more than your actual birthdate

💡David Robson is a science writer based in London, UK. He is d_a_robson on Twitter.

WEEKLY PICKS - 10

This post offers you a selection of recommended free online exercises, games, videos and resources so that you can improve your English language skills while having fun! ENJOY!

📜READING PICKS – Articles, blog posts, quizzes and more:

Article from BBC EARTH: The river that runs through the dawn of life, by Vivien Cumming. Every river has a story to tell and this one covers 500 million years.

Rocks sculpted by the Coppermine River took us on a journey through 500 hundred million years of Earth’s history, starting over 1.5 billion years ago when the earliest multicellular life was beginning to emerge. By studying and sampling the rocks along the riverbanks, and hiking into the wilderness using drones to map the area, we hoped to expand our understanding of early life on Earth.

The Coppermine River winds its way through the high Arctic landscape, cutting the easiest path through a remote part of the world until it reaches the Arctic Ocean and the Inuit settlement of Kugluktuk, where we ended our journey. (Continue reading)

Article from BBC FUTURE: How your age affects your appetite, by Alex Johnstone. Our relationship with food changes through our lives, and there are seven stages of life that affect how we eat.

Do you eat to live or live to eat? We have a complicated relationship with food, influenced by cost, availability and even peer pressure. But something we all share is appetite – our desire to eat.

While hunger – our body’s way of making us desire food when it needs feeding – is a part of appetite, it is not the only factor. After all, we often eat when we’re not hungry, or may skip a meal despite pangs of hunger. Recent research has highlighted that the abundance of food cues – smells, sounds, advertising – in our environment is one of the main causes of overconsumption. (Continue reading)

🎬 VIDEO PICKS – Short and fun videos:

LESS-THAN-5-MINUTE VIDEOS:

• David Crystal - Which English? (2:58 minutes)
• Why The Moon Turns Red During A Total Lunar Eclipse (3:08 minutes)
• 5 different ways to use the word wish: BBC MasterClass (4:56 minutes)
• BBC Masterclass: Formal and informal English (4:07 minutes)
• Why Are You Always Tired? (3:03 minutes)
• How languages evolve - Alex Gendler (4:02 minutes)
• Music and creativity in Ancient Greece - Tim Hansen (4:45 minutes)
• Everything Wrong With The iPhone (3:46 minutes)
• How art can help you analyze - Amy E. Herman (4:49 minutes)

5-TO-10-MINUTE VIDEOS:

• Sample B2 Speaking Test 6 Mad about shopping/consumerism (5:56 minutes)
• The Impressionists (5:33 minutes)
• English at Work: 10 Phrasal Verbs for the Office (8:46 minutes)
• BBC News Review: Prince says: talk about your feelings (9:21 minutes)
• Academic English - Prof. David Crystal on standard vs. non-standard English (5:38 minutes)
• What is Emotional Intelligence? (5:28 minutes)

A LITTLE LONGER BUT WORTH IT!

• Visit Germany - 10 Things That Will SHOCK You About Germany (11:28 minutes)
• Pre-Columbian Theater, Spanish Empire, and Sor Juana: Crash Course Theater #22 (12:03 minutes)
• The New Anatomy: Crash Course History of Science #15 (12:15 minutes)
• Why We Can't Invent a Perfect Engine: Crash Course Engineering #10 (12:54 minutes)

💬 VOCABULARY PICKS:

• Lightening or Lightning? (Brief explanation + top tips + short test!)
• Loose or Lose? (Brief explanation + top tips + short test!)
• Late, last, later, latter, latest (Choose the right word.)
• maybe and may be (Brief and clear explanation + quick interactive test! When you finish, click on “Next Test” for a new set of sentences)
• Beauty Salon (Things that happen at a beauty salon.)
• Beauty Salon 2 (Hair and Skin Care at a beauty salon.)
• Vocabulary Fill-in (DRAG + DROP) Exercise 3

💡 GRAMMAR PICKS – Assorted exercises and games:

• Linking Words of Contrast (However /Despite / Although)
• Linking Words of Reason (Because / Since / As / Due to / Owing to)
• Commonly confused words in English 1
• ARTICLE or NO ARTICLE? 2
• Articles with idioms 2
• Is 'To Do' Separable or Inseparable? - Phrasal Verb Quiz
• Some and Any Exercise 1
• Some and Any Exercise 2
• Prepositions Exercise 5
• Prepositions Exercise 6

MORE PICKS NEXT WEEK!

The US island that feels like Russia, by John Zada (from BBC Travel)

Unalaska Island in the remote Aleutian archipelago was part of an epic, but now mostly forgotten, military campaign during World War II.

(Credit:John Zada)

⇒ A slice of Russia in the US

After Danish explorer Vitus Bering and his Russian colleague Alexei Chirikov became the first known Europeans to visit the Aleutian Islands in 1741, waves of Russian fur traders flocked to the archipelago to hunt sea otters and fur seals. In the late 1700s, the islands became a colony of the Russian Empire. Today many inhabitants still have Russian surnames.

The Russian Orthodox Church followed the fur hunters, building small houses of worship across the islands and converting many Unangax to their faith. Although the US gained control of the Aleutian Islands when it purchased Alaska from Russia in 1867, the Russian Orthodox legacy has survived. Unalaska’s Church of the Holy Ascension (pictured above) is one of a few Russian Orthodox houses of worship that remain. Built in 1896, it is the oldest cruciform-style cathedral in North America and contains original icons and interior sections from earlier churches built on the same site in 1808 and 1825. (Credit: John Zada)

🔗 Go to FULL ARTICLE ⇒ The US island that once belonged to Russia

WEEKLY PICKS - 9

This post offers you a selection of recommended free online exercises, games, videos and resources so that you can improve your English language skills while having fun! ENJOY!

📜READING PICKS – Articles, blog posts, quizzes and more:

Article from BBC CAPITAL: Your vocal quirks could be costing you jobs, Video by Kat Sud, Maeve Burke and Bowen Li, research by Debbi McCullough. These vocal tendencies can cost you at a job interview, but is it fair to judge people based on these vocal habits? (Continue reading)

Article from BBC FUTURE: The dangerous diseases hidden in caves, by Zaria Gorvett. The rescued Thai boys faced infectious organisms underground and are now in quarantine – but which diseases could they have been exposed to, and how serious are they? (Continue reading)

🎬 VIDEO PICKS – Short and fun videos:

LESS-THAN-5-MINUTE VIDEOS:

• London | British Museum (3:45 minutes)
• The neuroscience of imagination - Andrey Vyshedskiy (4:48 minutes)
• Learners' Questions: Verb Patterns - full and bare infinitives (2:42 minutes)
• Commonly confused words (2:38 minutes)
• Learners' Questions: Using 'suppose' and 'supposed to' (3:07 minutes)
• 'I' or 'me'? (2:05 minutes)
• DIFFERENCES BETWEEN AMERICAN AND BRITISH GROCERY STORES (UK VS USA GROCERY STORES) (4:39 minutes)
• Vulnerability with Brene Brown (3:02 minutes)

5-TO-10-MINUTE VIDEOS:

• BBC 6 Minute English | THE MEANING OF CLOTHES | English CC | Daily Listening (5:58 minutes)
• Visit France - 10 Things That Will SHOCK You About France (9:27 minutes)
• Flight attendants Cabin crew service training (7:01 minutes)
• 8 Confusing Word Pairs Native Speakers Get WRONG (9:16 minutes)
• Talk about food expertise in 6 minutes (6:26 minutes)
• NORTHERN vs. SOUTHERN accents | British English Pronunciation (6:47 minutes)
• Looking for a job? Highlight your ability, not your experience | Jason Shen (6:30 minutes)

A LITTLE LONGER BUT WORTH IT!

• 5 Minute Biographies Season 2, Episode 1 - Theodore Roosevelt (12:42 minutes)
• How to Talk About Food - Adjectives to Describe Food in English - Spoken English Lesson (12:24 minutes)
• How language shapes the way we think | Lera Boroditsky (14:12 minutes)

💬 VOCABULARY PICKS:

• Vocabulary DRAG + DROP - FILL IN Exercise 1
• Vocabulary DRAG + DROP - FILL IN Exercise 2
• Vocabulary DRAG + DROP - FILL IN Exercise 3
• Text Completion DRAG + DROP Exercise 3
• Exercise on Accomodation
• Exercise on Eating Out
• Idioms - exercise 6
• Idioms - exercise 7

💡 GRAMMAR PICKS – Assorted exercises and games:

• Gerunds and Infinitives Exercise 4
• Make or Do Exercise 2
• Would and used to – past habits and repeated actions (2 EXERCISES)
• used to/to be used to exercise
• Mixed Articles 1
• Mixed Articles 2
• Articles with idioms 2
• Articles with idioms 3
• Prepositions Exercise 2
• Phrasal Verbs with the verb COME – Exercise (Choose the correct preposition.)
• Preposition 'OUT' - Phrasal Verb Quiz (Choose the correct definition for each phrasal verb)

MORE PICKS NEXT WEEK!

The language of mental or physical disability (from OXFORD Living Dictionaries)

Read full article: Avoid using dated or offensive words with these guidelines for use of specific terminology.

The language that is now considered suitable to refer to people with physical and mental disabilities is very different from that used a few decades ago. The changes are due partly to campaigns by organizations that promote the interests of particular groups of disabled people and partly to the public's increased sensitivity to the issues. People are now keen to avoid using terms that might reinforce any negative stereotypes of people with disabilities, in the same way that they try to avoid the racist or sexist terms that were once commonly used.

The word disabled itself came to be used as the standard term for referring to people with physical and mental disabilities from the 1960s onwards. It's still the most generally accepted term in both British and American English and has replaced terms that are now seen as offensive, such as crippled, handicapped, or mentally defective.

If you want to use appropriate language you not only need to avoid words which have been superseded, such as mongolism or backward. You should also try to do the following:

• avoid using the + an adjective to refer to an entire group of people, such as ‘the blind’, ‘the deaf’, or ‘the disabled’. This type of collective term is seen as dehumanizing: in essence, it reduces the people with a disability to the disability itself. It also ignores the individuality of those people by lumping them together in an undifferentiated group. The preferred forms are now ‘a person with …’ or ‘people with ……’ wherever possible, i.e. ‘people with sight problems’, ‘people with disabilities’, etc. If that isn't suitable, use ‘blind people’, ‘disabled people’, and so on.
• avoid using terms such as victim, suffer from, be afflicted with, or wheelchair-bound which suggest that the person concerned is the helpless object of the disability. Instead of suffer from, you can just say have:

Their youngest child has cystic fibrosis.

Another alternative is ‘be diagnosed with’:

In 1984, he was diagnosed with autism.

Rather than describing someone as wheelchair-bound, you can just say that they ‘use a wheelchair’.

• avoid using words which once related to disabilities, but which are now generally used as insults, such as mongol, cretin, spastic, schizo, dumb, etc.

GO TO FULL ARTICLE for Specific terms relating to disability
See also: OXFORD DICTIONARIES BLOG

WEEKLY PICKS - 8

This post offers you a selection of recommended free online exercises, games, videos and resources so that you can improve your English language skills while having fun! ENJOY!

📜READING PICKS – Articles, blog posts, quizzes and more:

Article from BBC CULTURE: The world’s most beautiful libraries, Cameron Laux. If like the writer Jorge Luis Borges you believe that Paradise is a library, fasten your seatbelt and prepare to be transported to heaven on earth. (Continue reading)

Article from BBC FUTURE: The ‘quiet eye’ of elite concentration, by David Robson. The way in which athletes can maintain their focus even under high pressure can help doctors, and it is of increasing interest to the military. (Continue reading)

🎬 VIDEO PICKS – Short and fun videos:

LESS-THAN-5-MINUTE VIDEOS:

• Why English is so hard to learn: adjective order (2:49 minutes) ⇒ See also: Grammar Pills: Order of Adjectives
• Learners' Questions: Adjective order (2:17 minutes)
• Why do we feel nostalgia? - Clay Routledge (4:08 minutes)
• London | Tower of London (4:02 minutes)
• Is a tomato a fruit or a vegetable? (1:25 minutes)
• 5 American Words That Are Rude In Britain (3:48 minutes)
• Can You Erase Bad Memories? (3:32 minutes)
• Are You Normal? (3:17 minutes)
• Goleman Six Leadership Styles (3:54 minutes)

5-TO-10-MINUTE VIDEOS:

• Where do superstitions come from? - Stuart Vyse (5:10 minutes)
• The benefits of a bilingual brain - Mia Nacamulli (5:03 minutes)
• The 71 Most AMAZING Innovations of All Time (6:41 minutes)
• 6 Minute Vocabulary: How to use linking words (6:06 minutes)
• Telling someone what to do - 52 - English at Work shows you the ropes (6:06 minutes)
• Top 10 Best Airports in The World (9:29 minutes)
• The myth of Icarus and Daedalus - Amy Adkins (5:08 minutes)

A LITTLE LONGER BUT WORTH IT!

• Visit Las Vegas - 10 Things That Will SHOCK You About Las Vegas (11:32 minutes)
• British Accents: MANCHESTER / MANCUNIAN (11:15 minutes)
• Humor and culture in international business | Chris Smit | TED x Leuven (14:42 minutes)
• How to stay calm when you know you'll be stressed | Daniel Levitin (12:20 minutes)

💬 VOCABULARY PICKS:

• Idioms - exercise 4
• Idioms - exercise 5
• Health and Medicine - Words
• Health and Fitness - Collocations
• Collective Nouns (List of official names of groups of things) ⇒ Collective Nouns Game
• Synonyms Matching 1
• Antonyms Matching Worksheet 5
• Health Problems (List of common types of health problems)

💡 GRAMMAR PICKS – Assorted exercises and games:

• EITHER/OR, NEITHER/NOR, TOO 1
• ARTICLE or NO ARTICLE? 1
• Articles with idioms 1
• First or second conditional? 1
• GERUND or INFINITIVE? 1
• Tag questions 1
• Quantifiers: More, most, the most 1
• Adjective or Adverb? (Are these sentences correct?)
• Time Prepositions 1
• Little / Few - Exercise
• A Little / A Few - Exercise 4
• Verb 'To Be' - Phrasal Verb Quiz (Choose the correct definition for each phrasal verb.)
• Quiz: Phrasal Verbs - Bring (Choose the correct answer.)

MORE PICKS NEXT WEEK!

The cost of ditching plastic, by Richard Gray (from BBC Capital)

What's the real price of getting rid of plastic packaging?

How much would it cost to switch to plastic alternatives? Richard Gray crunches the numbers.

Walking along a short section of stony beach, Claire Waluda stoops briefly to pick up something from between the rocks. It is a brightly coloured plastic bottle top – just one of hundreds of bits of plastic that she finds washed ashore on the remote, windswept island of South Georgia.

Located in the south Atlantic, on the fringes of the Antarctic, it is nearly 1,000 miles (1,500km) from the nearest major human settlement. Yet even here Waluda, an ecologist with the British Antarctic Survey, is finding worrying signs of our throw-away attitude towards plastic. Regularly she finds seals entangled in this debris or albatross chicks coughing up bits of plastic film.

These are just a few examples of the damage our throw-away relationship with plastics is inflicting on the environment. More than 78 million tonnes of plastic packaging is produced worldwide every year by an industry worth nearly $198 billion. Just a fraction of that is recycled while the vast majority is thrown away. Plastic litter now clutters every part of our planet, from remote parts of the Antarctic to the deepest ocean trenches.

WEEKLY PICKS - 7

This post offers you a selection of recommended free online exercises, games, videos and resources so that you can improve your English language skills while having fun! ENJOY!

📜READING PICKS – Articles, blog posts, quizzes and more:

Article from BBC TRAVEL: A country that doesn’t want to be happy, by Kate Leaver,
Finland came out on top in the 2018 World Happiness Report, but what if its people don’t agree? (Continue reading)

Article from BBC CAPITAL: The secret advantage of aiming low, by David Robson
Sports stars show us that it can sometimes pay to be a big fish in a small pond.
Watching nail-biting sports dramas play out this summer, you may struggle to see any parallel with your own career. What could a teacher, lawyer or engineer possibly learn from elite sports stars like a Raheem Stirling or a Simona Halep?
Yet some organisational scientists believe the rise of certain athletes – and footballers in particular – can offer success strategies for everyone, with some particular insights into a phenomenon known as the “Big-Fish-Little-Pond effect”. (Continue reading)

Article from BBC CULTURE: Five countries that set world culture, by Lindsey Galloway
Global influence is often measured by military, political or economic might. But for these countries, it’s their food, fashion or entertainment that most strongly impacts the wider world. (Continue reading)

🎬 VIDEO PICKS – Short and fun videos:

LESS-THAN-5-MINUTE VIDEOS

• Plato’s best (and worst) ideas - Wisecrack (4:48 minute)
• You're Not What You Think You Are (3:15 minutes)
• The history of tea - Shunan Teng (4:57 minutes)
• Amazing Facts to Blow Your Mind Pt. 2 (2:23 minutes)
• Amazing Facts To Blow Your Mind Pt. 3 (2:19 minutes)
• BBC Masterclass: Formal and informal English (4:07 minutes)
• BBC Masterclass: Be polite - how to soften your English (4:25 minutes)
• Customs at PQ International Airport (2:49 minutes)
• English: At the airport (1:42 minute)
• You Have Arrived (4:14 minute)

5-TO-10-MINUTE VIDEOS:

• The myth of Cupid and Psyche - Brendan Pelsue (5:32 minutes)
• The great conspiracy against Julius Caesar - Kathryn Tempest (5:57 minutes)
• BBC 6 Minute English - "Brain Training" with English Subtitle (6:05 minutes)
• DIFFERENCES BETWEEN BRITISH AND AMERICAN CULTURE (UK VS USA) (5:06 minutes)
• How Did You Get Here? (5:55 minutes)
• The Four Love Types: Explorer, Builder, Director, And Negotiator (6:16 minutes)
• Visit Denmark - 10 Things That Will SHOCK You About Denmark (10:20 minutes)

A LITTLE LONGER BUT WORTH IT!

• London Accents: RP | Cockney | Multicultural London English (12:10 minutes)
• The Economics of Airline Class (11:37 minutes)
• 20 MORE Words Brits and Americans Say Differently (12:43 minutes)

💬 VOCABULARY PICKS:

• Vocabulary related to education (List of vocabulary items related to education) ⇒ Practice: Education
• Idioms - exercise 2
• Idioms - exercise 3
• Vocabulary Fill in Exercise 2
• Someone / Anyone
• Something / Anything
• Somewhere / Anywhere

💡 GRAMMAR PICKS – Assorted exercises and games:

• Prepositions of time Exercise 9
• Prepositions of time Exercise 10
• Articles with Geographical Names Exercise 1
• Articles with Geographical Names Exercise 2
• have to/must Quiz
• Relative Adverbs
• Participles
• Infinitive and Gerund
• Verb 'To Do' - Phrasal Verb Quiz – 1 (Choose the correct definition for each phrasal verb)
• Quiz: Phrasal Verbs – Do - 2 (Choose the correct preposition or particle for each phrasal verb)

• Random Phrasal Verb Quiz (Test your understanding of phrasal verbs with these random phrasal verb quizzes. Each time you 'start again', it will show you a new quiz generated from a phrasal verbs database.)

MORE PICKS NEXT WEEK!