An ad that displays in a secondary browser window. Pop-up ads display in front of the initial browser window while pop-under ads display behind it.

The position of an individual advertisement (or other non-program content) within a commercial pod. Individual Pod positions will be defined by the content provider.

A collection of non-programming content whether commercials billboards PSAs etc. that are inserted as a block of seconds or minutes before during or after a program.

A term describing the object that represents a piece of inventory. Publishers embed placements into web pages' ad tags. This same object may also be called an ad tag or an ad unit but this is slighting inaccurate as placements contain tags and represent units of available ad space.

A pixel is a way to track user data. Originally all pixels were literally snippets of code that called for a 1X1 transparent pixel to be delivered to a webpage by a third-party server. Nowadays pixels may either be literal pixels or be javascript based. When the pixel loads the third-party server can record information such as the IP address of the user's computer URL of the page and time the page was viewed. See also conversion pixel and segment pixel.

See personally identifiable information.

This term usually refers specifically to a piggybacked pixel. When pixel A has pixel B piggybacked on to it then the firing of pixel A causes the firing of pixel B. This second firing can either be via a redirect or a server-side firing. Piggyback pixels may be used for tracking conversions in secondary systems.

Information that can be tied to an actual named person rather than an anonymous user ID. For example names social security numbers residential addresses and driver's license numbers would be considered PII. Many jurisdictions worldwide have explicit policies banning the use and tracking of PII in online advertising and numerous ad traffickers do as well.

The redirecting of an impression back to an ad server when no acceptable bid is received from a mediated bid in order to allow the next highest bidder a chance to win the impression. See also default tag.