This sounds like a very simple question but it can be surprisingly confusing. People describe a lot of things as “sex”.
Let’s get one thing out of the way to begin with: it is often used interchangeably with the word “gender” although usually in a physical or biological sense, relating to the body you have, rather than the identity you feel. See our separate post on gender for more on this.
But that is not typically what people mean when they ask “do you know what sex is?”- they are more often asking “do you know what having sex is?”
The traditional answer is that having sex means sexual intercourse – in short, a penis being put into a vagina – the way that reproduction happens (see Where do babies come from? if you’d like more information on this).
And, certainly, this kind of penetrative sexual intercourse is one way to have sex. But it’s by no means the only way to do it.
For starters, there are many different sexualities – some people with a penis like other people with penises. Some people with a vagina like other people with vaginas. Some people like both. And, of course, some people don’t like sex at all.
The reality is that people’s opinions vary on what they consider to be “sex” and there is no one “right” answer. It’s a personal thing, and different people like different things.
Some would say that sex does not have to be physical at all – that it can be the sharing of sexual ideas, thoughts or fantasies without even touching another person.
In the lead up to having sex, there is foreplay, and where that ends and “sex” begins is a matter of opinion.
And, if and when it comes to touching each others’ bodies intimately, there is a wide range of things that different people like. We’ve already mentioned sexual intercourse, but there’s also manual sex (using your hands), oral sex (using your mouth), anal sex (involving the anus or bottom) and endless different ways of doing all of these things, and others.
The important thing is to realise is that there is no “one size fits all”.
Different people like different things, and the only way to find out what a person thinks of as “sex”, or what kind of sex they like is to ask them. And if you are going to be sharing sexual experiences with someone else, then spend time communicating with them, so you both know what you are expecting, and so you can both enjoy it to the full.