What is a task dependency?

Task dependencies show what must be done before a given task and what will be done after the task is complete. Project managers can create dependencies between any two or more tasks in a project.

Task dependencies allow you to establish relationships between tasks. This can help to frame a task in the context of a larger project plan.

There are two types of task dependencies:

Predecessors are tasks on which another task depends.
For example, before you can complete the task "Finalize project plan," you might need another project member to complete the predecessor task "Hire new staff."
Successors are tasks that depend on your task.
In this example, "Finalize project plan" is a successor task to "Hire new staff."

Note: Task dependencies and tracker artifact dependencies are different things.

For tracker artifacts, an artifact with dependencies (a "parent" artifact) can't be considered closed unless all of its dependent artifacts ("children") are closed.
For tasks, a dependency means one task can't start until another task is completed.

Important: A task cannot be dependent on itself. You cannot make a task both a predecessor and a successor to another single task. If you attempt to do so, you will receive a circular dependency error.