Lead/lag links between tasks on the same bar
When you draw a link between two tasks on the same bar, the link has lead/lag time ensuring that the second task does not begin until the first task is finished:
If you set up a lead/lag link which would cause the tasks to overlap, this link is ignored by the reschedule and the tasks are positioned end to end.
Lead/lag links between tasks with different calendars
Editing lead/lag type and time
How lead/lag is handled when you export to another project management application