There's a lot of terminology around gender that can get a confusing from time to time. Here's a few of the most common terms that are really good to understand:
An umbrella term for those whose gender identity doesn't fit the 'man' or 'woman' binary. Can include those who identify with some aspects of binary identities, or who reject them entirely. The most common pronoun used is 'they', but there are many different pronouns. Sometimes shortened to 'NB' or 'enby'.
In grammatical terms, these are simply words used when referring to a noun, for example I, you, she, he, they. Respecting and using someone's correct pronoun is vital.
An umbrella term to describe someone who identifies as a different gender than the one assigned at birth. Can also include those identifying as non-binary, gender-fluid, agender, trans man or trans woman among many other identities. A shortened version of transgender.
The varying ways a trans person may change their social presentation to match their gender identity. This may include changing their name or pronouns, changing the clothing worn or may involve hormone therapy or surgery. There are multiple, equally valid, ways of transitioning.
An umbrella term that can describe anyone who is not straight and / or cisgender or anyone who does not find their identity under a single label or labels.
A medical term used to refer to chromosomal, hormonal or anatomical characteristics that classify someone as 'female', 'male' or 'intersex'. Often referred to biological or physical sex or simply as 'sex assigned at birth'. Separate to gender.
Describes a person born with variations in their sexual characteristics, including hormones, chromosomes or physical anatomy, that are outside of what is generally considered to be a female or male binary.
The internal perception of gender; a sense of 'being' a woman, a man or someone who doesn't fit this binary as is non-binary. May or may not correspond with the identity assigned at birth and is different to both biological sex and sexuality.
Someone who identifies as the gender identity and biological sex they were assigned at birth. One way to look at it is as someone who is not trans. Often shortened to 'cis'.