Two (or more) people roll play that they are having sex. It's like sextexting in a few ways. Online sex is done by messaging through a chat box of some sort (it.
Sexicon for Lovers and Others - Dictionary of sexual terms, a second dictionary of equivalents of the "F" word and thesaurus.
Comprehensive list of synonyms for sexual activity, by Macmillan Dictionary and the use of the Internet to have sexual experiences, for example by having a.