An introduction to computer audio
Often tracks on a CD are played without any intervening silence at track change.
Live albums are an example.
In classical music consecutive movements are sometimes played as one.
In case of computer audio, each track of a CD becomes a file.
Standard there is a gap between two files.
Gapless playback is a property of the media player to play these files gapless.
Not all media players support this.
Even if the media player supports it, it might not apply to all supported audio formats.
Gapless Playback - Hydrogenaudio