Tracks

Any recording system uses one or more tracks to record and play back audio information.	A track on magnetic tape is a path containing one channel of this information. Multitrack recorders record several of these paths or tracks on one piece of magnetic tape.
The more physical area provided for a track on the tape, the greater the signal to noise ratio will be, resulting in less tape hiss. As the tape width provided for a track doubles the corresponding level of tape hiss drops by 3 db. So if you want to use a multitrack system with a large number of tracks a wider tape width will be necessary.	For a given track density several tape widths and corresponding tape transport systems are available. The wider tape formats will generally give higher fidelity than narrower ones when used at the same tape speed.

Track width

full-track mono
records one track over the whole width of the tape in one direction of tape travel only

half-track mono
records one track in one direction of tape travel and another in the opposite direction.
each track uses approximately half the width of the tape with a guard band between the two to prevent crosstalk

half-track stereo or 2-track stereo
records two tracks in one direction.
each track uses approximately half the tape with a guard band between them.
used for stereo masters

quarter-track stereo
records two tracks in one direction and another two tracks in the opposite direction.
each track uses approximately one quarter of the tape with guard bands between each track.

multitrack
records four or more tracks in one direction.
divides the tape width into the number of tracks minus the widths of the guard bands.

Track widths

Audio tape is manufactured in a variety of widths. Each width can be used in several different track formats as listed below:

1/8"	quarter-track stereo cassette 4-track, 8-track cassette
1/4"	full-track, half-track mono half-track stereo quarter-track stereo 4-track,8-track
1/2"	4, 8, 16 tracks
1"	8, 16, 24 tracks
2"	16, 24, 32, 48 tracks