What is Coachella?

Coachella is a town in California. It's also the name of a large music festival held there every year.

What is the DNS?

The DNS is the system which looks after the names of sites on the Internet. For example, whenever you look at a website, you are using the DNS to look up the website's name and find which webserver to talk to.

DNS stands for "domain name system".

What is chlamydia?

Chlamydia is an infection that you can get if you have sex without a condom and the other person already has it. Many people have chlamydia. Often they don't know, because there are no signs that they have it. But it's easy for a doctor to test whether you have chlamydia. And it can easily be treated.

If you get chlamydia, it's important to get treated, otherwise you may not be able to have children. You can be tested by your GP, or by the GUM clinic in a hospital. If you live in the USA, Planned Parenthood can help you.

You can greatly reduce your chances of getting chlamydia in the first place if you use a condom each time you have penetrative sex.

What is distilled water?

Distilled water is water which has been purified by boiling it. Because many of the impurities you can find in water won't have boiled as well, when you turn the steam back into water it should be more pure than before.

You use distilled water in steam irons, and in car batteries. Some people also drink it, especially when the ordinary water nearby is salty or dirty.

What is twerking?

Twerking is a dance move where you twist your hips and jerk your body. It was made popular in the 1990s.

What is a metaphor?

A metaphor is when you say that anything is something it really isn't, in order to describe it.

For example, saying that the fog is a cat, or that life is a battle, is using metaphors. This tells people that the fog is a bit like a cat: grey, perhaps, and not waiting to be invited. Life is a bit like a battle because it's dangerous.

But if you say the fog is like a cat, or that life is like a battle, that's a simile rather than a metaphor. Metaphors and similes work rather similarly.

What is a prime number?

A prime number is a number which can't be divided exactly by anything but itself and 1. It must be a whole number (an integer) and greater than zero (positive).

For example, 2, 3, 5, and 7 are all prime. But 4 is not, because it can be divided by 2.

Any whole, positive number which is not prime is called a composite number. So, 4 is a composite number.

1 is not a prime number.

Prime numbers go on for ever. There is no limit to how many there are. If you kept counting for ever, you would keep on finding new prime numbers.

What is a hashtag?

A hashtag is a word within a message which is used to organise that message. So that it doesn't get confused with an ordinary word, it has a hash mark before it: "#", which is called "pound" in the USA.

For example, if I wrote "I really like cheese", I could add a hash before "cheese": "I really like #cheese". Then if anyone clicked on "#cheese", they would be taken to all the other posts containing the same hashtag.

Sometimes people use hashtags as a sort of joke, commenting on the post, rather than for organising their posts. For example, "My cousin has broken my computer. #idiot".

Facebook and Twitter both support hashtags.

A hashtag is used much like a tag. But tags are usually separate from the body of the post they're classifying, whereas hashtags are part of it.

Hashtags are an example of a folksonomy, a system where the classification is brought about by the collective action of its users, rather than being centrally imposed.