A single is a standalone track release. Singles are usually released to promote an artist’s upcoming album or to gain exposure for a particular song.
Singles are a way to generate buzz for an upcoming album. This buzz generation is known as an album rollout. These songs are usually part of the planned album and are released separately to gauge audience response. They are typically more radio-friendly and likely to be played on mainstream media outlets.
On the other hand, singles are a way to stay relevant. When an artist is in the process of putting together a project, they will often drop singles to keep in public discourse. These releases may not be tied to an album but are a way to keep their fans interested.