If the gender assigned at birth does not match to how a person feels, then the person might be transgender, non binary, gender queer or gender fluid. The term refers to what someone experiences inside, so someone who has just discovered these feelings in themselves is just as transgender as someone who has started their transgender journey years ago.
Transwoman, transman, or something else?
Transgender people must be indicated in the way in which they identify themselves. A transwoman is someone who was born in a masculine body, but who might feel like she is a woman. She therefore wants to be treated as a woman. A transman is someone who was born with a feminine body, but who might feel like a man. He wants to be treated like a man. Whether that person is already in transition does not matter.
People who identify themselves as neither male nor female (for example, they feel both at the same time, or neither of them) might also be transgender, but they might also identify as non-binary. Binary means there are 'two options', which means either you are male or you are female. Non-binary people do not adhere to either of these two options. They are transgender because their feelings do not match their assigned gender. It is polite to ask someone how that person wants to be treated and what their pronouns are if you are not sure what their gender is or how they identify.
When someone feels very unhappy or uncomfortable in their own body because they feel their body doesn't have their preferred gender, then that person experiences gender dysphoria. An example is being able to grow a beard while you feel like and know you are a woman. This mental distress is defined in the DSM-5 (2013), the psychology textbook used worldwide. This allows psychologists to diagnose and refer people who are transgender so that the help they need is covered by health insurance. To reduce gender dysphoria, people can go into transition. There is physical dysphoria and social dysphoria, for which the medical transition and social transition are the solution.
Gender identity disorder
Due to the confusion with gay, straight and other forms of sexuality, the DSM IV (American Handbook for Diagnosis and Statistics of Mental Illnesses) is now talking about gender identity disorder instead of transsexuality. Transsexuality, after all, has only indirectly to do with sexuality and nothing to do with the sex of the people to whom one is attracted, but everything with one's own gender identity.
Going into transition
When a transgender person goes into transition, they start with the change to their desired gender. This has three sides: medical, social and legal.
The medical process usually consists of the use of puberty inhibitors (12 to 16 years old), hormones (minimum 16 years), and one or more operations (minimum 18 years).
Before being eligible for surgery, one must live for at least a year as the desired gender. This is a requirement set by hospitals. In practice, this often means a new name, a new wardrobe (for which you can get the necessary undergarments and prostheses at UNTAG), a different hairstyle, a coming-out with friends and family, and above all a lot of self-development. Of course, the social side of the transition can also take place without the involvement of a hospital. For example: a transgender girl (who was born in a masculine body) tells you, after consulting with her mentor in the class that from now on she wants to be treated as a girl and that she will go to school in women's clothing. She has chosen a new name, but she cannot use it everywhere, because that name is not yet on her ID card. Due to her age, it can take a long time before she can change her data and before she can change anything in her body.
From the age of 16, and after an expert psychologist has determined that the person is transgender, that person can legally choose a change of gender and new first names. This information will then appear in the birth certificate, ID card, passport, driver's license, etc. Note that this is different in each country.
People who do not want a complete medical transition can choose not to use hormones but to undergo surgery, or vice versa. Changing data also remains optional.