A hate crime (also known as a bias-motivated crime) is a prejudice-motivated crime, which occurs when a perpetrator targets a victim because of his or her membership (or perceived membership) in a certain social group.
Examples of such groups can include and are almost exclusively limited to: sex, ethnicity, disability, language, nationality, physical appearance, religion, gender identity or sexual orientation. Non-criminal actions that are motivated by these reasons are often called "bias incidents".
"Hate crime" generally refers to criminal acts which are seen to have been motivated by bias against one or more of the types above, or of their derivatives. Incidents may involve physical assault, damage to property, bullying, harassment, verbal abuse or insults, mate crime or offensive graffiti or letters (hate mail).
A hate crime law is a law intended to deter bias-motivated violence. Hate crime laws are distinct from laws against hate speech: hate crime laws enhance the penalties associated with conduct which is already criminal under other laws, while hate speech laws criminalize a category of speech. Hate speech laws exist in many countries. In the USA, hate crime laws have been upheld by both the Supreme Court and lower courts, especially in the case of 'fighting' words and other violent speech, but they are thought by some people to be in conflict with the first amendment right to freedom of speech, so they have occasionally been overturned as unconstitutional.