The next four letters stand for transsexual, queer, questioning and intersex.

I believe (please correct me if I'm wrong) transexual people feel that they are not the gender which they were assigned at birth, but this actually comes from a neurological condition that is treated medically, or they can have a gender realignment surgery.

Queer is an umbrella term that refers to all sexualities and genders other than straight and cis.

Questioning, when used in lgbt sense, means someone is questioning whether or not they are queer.

There are actually two different flags for questioning people, the one above (removed as the p*dos wanted to claim it) is for questioning sexuality and the one below for gender.

Intersex is a term that refers to someone who was born ambiguous (born as both male and female), meaning they can identify as male, female, or other. They can choose to get a surgery to assign themselves to a gender or not, but sometimes the choice is made for them by their parents at birth.

I hope I got all this and the flags right!
Again, please correct me if I have put down any false information