An editing mode found in Pro Tools software. Grid Mode works like a lot of MIDI sequencers. Everything snaps to a user defined grid or quantization value. You can define the grid based on musical values (eighth notes, for example) or time code values. This mode is also handy for loop based work; it allows the added flexibility of being able to drop regions wherever you want, but it keeps them locked in to the musical timing of the piece. A lot of engineers use this mode when editing things like drum parts for timing (a very common use of Pro Tools) because it makes it really fast to drop individual drum hits to specific musical timing values that are related to the song. If you place a region over another region the first region will be cut off at the point where the new region starts and/or ends. The three other major editing modes in Pro Tools are Spot Mode, Shuffle Mode and Slip Mode.