Sexual disorders are a wide range of conditions and deviations in human sexuality. Sometimes sexual disorders are related to a past event or trauma that has paired with sexuality and causes issues or difficulty with sexual activity (such as an aversion to sex after experiencing a rape).
Sexual dysfunctions such as erectile dysfunction and sexual arousal disorder are considered to be sexual disorders. Paraphilias such as pedophilia are also considered sexual disorders. Other examples include hypoactive sexual desire disorder and sexual aversion disorder.
It is important to note that some normal and healthy sexual behaviors are considered to be deviant and sexual disorders by some people when in actuality they do not meet the criteria. For example, some may consider an individual with an unusual fetish to be suffering (masochism) from a sexual disorder. But if this sexual behavior is not harmful to other people and does not cause distress or harm to the individual then it isn't considered a sexual disorder.
Sexual disorders are treated using therapy or medication dependent on what type of condition it is.