This article is from the Dissociation FAQ, by Discord (firstname.lastname@example.org) with numerous contributions by others.
Abuse comes in all sorts of different types, results in different
effects, and is both perpetrated by an experienced by people from every
age group, racial/ethnic group, religious group, country, gender, and
sexual orientation. Abuse may be more common in some of these groups, as
well as more commonly perpetrated by people from some groups, but anyone
can abuse, and anyone can be abused.
A simplistic definition of abuse would be any action that is done to
someone without their full, informed consent. I call this simplistic in
part because it fails to define what constitutes consent.
Generally speaking, abuse is harmful. There are some actions that some
people may consider abusive, that subjectively may not seem harmful (to
either the perpetrator or the victim of the abuse).
It is thought that nearly 1/4 of all people in the U.S. have been (or
will be at some time in their life) abused in some way. Since abuse is
often hidden both by the perpetrator and the victim, there is not
currently a realistic way to measure just how much abuse occurs, the
usual length of the such abuse, the gender of abused and abuser, and so
forth; many studies have been done on the issue and they have turned up
many conflicting answers.