Masturbation is the act of bringing yourself to orgasm. It's sex with yourself, usually by yourself.
In slang, there are hundreds and maybe thousands of vulgar terms for masturbation, almost all of which are inappropriate in most situations. Society's attitude towards masturbation has changed a lot over time. People used to think it was unhealthy, and some religions considered it a sin. Some still consider it wrong, and not everyone wants to talk about it, but most people now understand that masturbation is a harmless part of life.
