More details can be found by clicking the game's name.

Local: The game supports local co-op gameplay on a single console.
Online: The game supports online co-op over an internet network.
Split: The Local co-op features a split screen.
JIP: Joinable in Progress. The game allows you join up for Co-Op anytime, it doesn't need to be started as a co-op session.
CSC: Co-Op Specific Content. The game features content that is specific to Co-Op gameplay.
SPC: Single Player Content in Co-Op. The game's single player campaign is available for Co-Op play.