See also: Visit
CIMM DEFINITION: A measurable segment of available content seen by a unique viewer, by viewing device. Today the viewing device is the set-top. In the future, the device will need to be defined and specified. (Source: CTAM Advanced Cable Solutions Consortium, DAI Metrics)

2: 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. (Source: IAB)

3: A series of transactions performed by a user that can be tracked across successive Web sites. For example, in a single session, a user may start on a publisher’s Web site, click on an advertisement and then go to an advertiser’s Web site and make a purchase. (Source: IAB)