Tempo
Tempo can be controlled via the DAW in one of two mutually exclusive ways. The simplest is to set the entire project to a fixed tempo. Here you simply set the beats per minute (bpm), and that is the tempo of your entire project.
The more advanced method of manipulating tempo is via the tempo track. This is often a built-in automation track; however, it works a bit differently than normal automation tracks. It cannot be deleted and isn't attached/associating with any of the independent tracks - it is tied to the project itself. It can only control the tempo parameter. This allows you to change tempo throughout a song, as well as gradually speed up or slow down.
As mentioned in drum programming, manipulating tempo is a good way to help automated instruments sound more human.