Trans people are individuals who strongly feel that they are, or ought to be, the opposite sex.  The body they were born with does not match their own inner conviction and mental image of who they are or want to be. 

Nor are they comfortable with the gender role society expects them to play based on that body.

This dilemma often causes individuals intense emotional distress and anxiety and often interferes with their daily living.

Trans people often say that they feel trapped.  Destined to live out their lives "imprisoned in the wrong body" unless they correct the situation with hormones or surgery.

Most people were painfully aware of their gender incongruity from early childhood, while others become aware in early to late adulthood.

Trans identity cannot be attributed by others!  It is our own deeply held conviction and deeply felt inner awareness how we identify on a gender spectrum.

Trans identity is private and internal.  It is felt, not seen.  It cannot be deduced from how a person looks, moves, dresses, or behaves.  The only way to know a person's gender identity is if they tell you!