Bouncing tracks   

It seems inevitable that no matter how many tracks are available on the recorder a time comes when we would like more for a particular project.  

One solution to this dilemma is to bounce tracks; which means mixing several tracks onto one or more open tracks in order to free up more tracks for recording. 

 
For instance, suppose you're recording a vocal ensemble of six independent voices and an instrument ensemble of six instruments. Ideally you need at least twelve tracks but have only an eight track recorder for the production. 

One solution is to record the six voices using tracks one through six and then mix them together in a stereo pair to the two remaining tracks seven and eight. Tracks one through six can now be erased and made available for the instrumental sextet.  (The downside of course, is a loss of flexibility once the original tracks 1-6 are gone.)