1) a sequence of Internet activity made by one user at one site. If a user makes no request from a site during a 30 minute period of time, the next content or ad request would then constitute the beginning of a new visit 2) a series of transactions performed by a user that can be tracked across successive websites. For example, in a single session, a user may start on a publisher's website, click on an advertisement and then go to an advertiser's website and make a purchase. See visit.