Adding a dependency using drag and drop

A dependency (often called a linked task) determines how a task in a task plan is scheduled, in relation to all other tasks in the task plan. A dependency is based on a task's start date and/or finish date. A dependency that determines how other tasks in a task plan are scheduled is called a predecessor. A dependency that relies on another task's start date or finish date to determine how it can be scheduled is called a successor.

To add a dependency from the Gantt chart

Open the Projects module.
Select an item.
Select the Task Plan tab.
In the task plan, from the Gantt chart, select the task to which you want to add a dependency and drag it to another task in the Gantt chart.
You can verify the settings of the dependency using the Task Dependency dialog box. Click the line that represents the dependency to open the Task Dependency dialog box.