When you want to put an extra hairpiece into your hair, it’s essential to create a “track” that the extended hair piece can be sewn in to. This track— or hem—works like an anchor to hold the new hair in place.
In the realm of magnetic storage media, such as tapes or disks, the path traversed by the playback head is transformed into a magnetic representation of the input signal, leading to the reproduction of the original recorded signal when the track is scanned.