A process for hiding the physical cuts in a finished film by splitting successive shots onto two separate reels. In addition, checkerboarding also makes possible effects like dissolves, wipes and fades.
The technique of intelligently placing dissimilar audio material on separate tracks
During the final mix, these different tracks can be processed differently to achieve a smooth and cohesive result
Especially helpful when an overlap or crossfade between sounds is desired.
Basically, this is cutting up your sound (which typically comes in one big track) into little pieces like single phrases of dialogue, and giving each actor's sound its own audio track. Effects and music should also have their own tracks.
