Poly bag

Poly Bag " Alternative to paper envelopes made of transparent plastic called "polyethylene."
Pop-Up " Ad or message that "pops up" in your browser window.

Poly bag
When designated issues of a newspaper or magazine are inserted into a plastic bag. Usually to accompany advertiser‘s inserts/FSIs, etc. In some instances, advertising can be printed onto the outside of the bag.

Poly Bag: An outside mailing envelope made of polyethylene instead of paper.
Pop-under: A window that appears under the browser window.
Pop-up: A window that pops-up over the browser window.

See also: Control, Insert, List, Deliverable, Seeding