backgrounder

A briefing or document typically provided prior to a meeting or other event that gives basic details on subjects that are likely to be mentioned.

One of the President's aides gave us a ten-minute backgrounder on the dairy industry before the meeting.

A person employed to draw backgrounds for a comic or cartoon.

[…] backgrounders paint static background scenes, and then the animation components are layered on top […]

A cattle farmer or rancher who runs a backgrounding operation.