Definition
Revenge porn refers to content (e.g., photographs or videos of a sexual nature) posted online without the subject's consent to embarrass or humiliate someone — often a former boyfriend/husband or girlfriend/wife.
Overview
Some websites, set up specifically for these kinds of photos or videos, post a victim's name, address and links to social media profiles along with images, and somewebsites charge a fee to have the materials removed.
New Jersey was the first state to criminalize revenge porn. A complete list of state legislation relating to revenge porn is provided by the National Conference of State Legislatures here.