Pro Tools lets you mix down by
recording a mix to new audio tracks or by
bouncing a mix to disk.
This is the process of submixing and recording the submix to new audio tracks, as you would any other track input signals. This method requires available tracks, voices, and bus paths to accommodate the submix and the new tracks. While recording to tracks, you can manually adjust mixer or other controls.
The Bounce to Disk command lets you write a final mix, create a new loop, print effects, or consolidate any submix to new audio files on disk. This method lets you write all available voices to disk without holding any in reserve.
Any available output or bus path can be selected as the bounce source. Sample rate, bit depth, and other conversion processes can be applied during or after the bounce. Though you can hear the bounce being created in real time, you cannot adjust mixer or other controls while bouncing to disk.
Use Bounce to Disk if you need to convert the bounced files, or if you do not want to manually adjust mixer controls during the mixdown.