Gender spectrum and non-binary
If we imagine gender is a spectrum with male and female at either end, some people feel like they fit a different category than the gender they were given at birth and move from one side to the other and some people feel they are a mix and somewhere on the scale.
Some people don’t feel like they fit on the spectrum at all and reject those terms all together. Some people refer to their gender as “non-binary” to describe when their gender falls outside the gender binary system. These people can sometimes use gender-neutral pronouns such as “they” instead of “him” or “her”.