Types of dependencies

Finish→Start: The first task must end before the second task can start; the tasks must not overlap except at the instant the first one ends. This is the most common type of dependency, and the kind that you get when you connect two selected tasks by clicking the Connection button in the toolbar.

Finish→Finish: When the first task ends, then the second one can end; the tasks may overlap.

Start→Start: Once the first task has started, the second one can start; the tasks may overlap.

Start→Finish: Once the first task starts, the second one can finish; the tasks must overlap at least at the instant the first one starts.