A strategy guide is a book or internet guide that has an in-depth coverage on a particular video game. These guides typically have lots of in-game screenshots, maps, and special notes and cover just about every section of the game. There may also be a checklist for completing tasks and/or collecting items as well as a character guide and/or bestiary.
Some notable strategy guide companies are Nintendo Power, Bradygames (later merged with Primagames) and Piggyback Entertainment.