Gender dysphoria, which is also known as 'gender identity disorder' or (GID), is a medical diagnosis that describes an experience of anxiety, confusion, and discomfort about the discrepancy between one's biological sex, and one's self-defined gender identity which does not match their biological sex.

Gender confusion, and conflict may ebb and flow over the years, with some periods of time being more difficult than others.  Eventually, however, it will begin to permeate every aspect of life, causing increasing amounts of distress, confusion, and anxiety for the gender incongruent person. 

For diagnostic purposes, the mental health community relies on a manual commonly referred to as the DSM-IV, to classify someone as having Gender Identity Dysphoria (GID).  The primary criteria for this diagnosis are strong and persistent cross-gender identification.  This means the person wants to be, or is insistent they already belong to, the opposite sex.  A person must be persistently uncomfortable in their current gender role, and feel that it's not congruent with their physical self.  This diagnosis will not fit if a person is motivated to transition for the purposes of experiencing a cultural advantage of the other sex. Likewise, the diagnosis is not appropriate for someone with intersex conditions.  There has to be evidence of clinically significant distress, or damage to important aspects of the person's life to diagnose gender identity disorder. 

Gender dysphoria is an overwhelming and widely misunderstood condition that causes significant distress for those experiencing these conflicts.  It is common for gender dysphoric men and women to develop anxiety and depression.  The longer these issues go un-addressed, the more severe the conflicts can become.  Many people make choices to affirm their biological sex by over-compensating for their gender identification with the other sex.  Men may go to extremes to prove their masculinity, including marriage and fatherhood, and biological women may also go to extremes  to prove their femininity.  

Transsexualism can be defined as incongruence between the biological sexual differentiation and the gender identity.  In a nutshell, a man or woman who experiences the feeling that they have the mind of one gender and the body of another.  The intensity of conflict for a transsexual is such that relief can only be experienced by changing their body to match their mind.

Transitioning one's gender role typically involves a regimen of Hormone Replacement Therapy (HRT), which may or may not be followed by Sexual Reassignment Surgery (SRS) depending on how a person defines their own gender.   Some men and women are able to find relief for their gender-incongruence by changing their physical self enough to be perceived by the world in the gender that is most true for them, regardless of the genitals they have.  Others, despite the private nature of what one's genitals are, feel persistently uncomfortable until their entire physical self, genitals and all, match their gender identification. 

There are no studies, currently, that reflect an accurate representation of the percentage of people who experience gender dysphoria.  Because of the highly-stigmatized, often shame-based nature of this condition, it is common for those with gender issues to censor and conceal their feelings, thus compromising our ability to know how many people are experiencing this pain.