When people refer to someone’s sex (sometimes called biological or physical sex), they’re talking about that person’s identity based on their physical characteristics (for example, having a penis, vagina, beard or breasts) as well as their genes and hormones.

Many people think of ‘male’ and ‘female’ as the only sexes, but that’s not actually true. some people have genetic, hormonal and physical features typical of both male and female at the same time, so their biological sex isn’t clearly male or female. This is called ‘intersex’. This is why we should never assume what sex someone is, whether you think they’re male, female or intersex.