Justice League: A Better World
The Bleed is an interdimensional plane that forms the barriers to parallel dimensions. It is also spatially connected with the Multiversal Nexus and the Nanoverse.
The space between dimensions, occasionally named Limbo, has appeared several times in the Silver Age, first in Justice League of America #21. The concept of “The Bleed” (and its red coloring) was created for the Wildstorm Multiverse in The Authority #1. Following the merger of Wildstorm into the 52 Multiverse as “Earth-50”, the Bleed was added to DC proper. In the New 52, the term is more clearly defined as the space between the multiversal worlds (also encompassing the House of Heroes and the Rock of Eternity) bordering the Sphere of the Gods at the Speed Force Wall.