Activity
An activity is a single atomic unit of work to be accomplished.
Finish activity
Last task in a networked schedule.
Hammock
This task type is used to create a pseudo-summary over detailed tasks that are not subordinate to this task.
Milestone
A milestone is a specific goal to be accomplished within a project. Milestones typically have zero duration.
Start activity
First task in a networked schedule.
Summary
A summary task summarizes detailed subordinate activities.