Task Dependency means a set of predefined relationships between two or more interrelated tasks to determine a range of conditions and rules for implementation of the tasks. For example, any next task cannot be started until the previous task is finished, either completely or partially.
A person or a group of individuals involved in performing dependent tasks should take into account existing conditions and relationships between the tasks before and during implementation in order to do the tasks as planned.
Task dependency is critical to successful project management. It allows creating a logical relationship between events and activities within a project. There can be four possible types of logically dependent project tasks. These types are:
- Finish to Start: when one task is finished another dependent task is started.
- Finish to Finish: two dependent tasks are finished simultaneously.
- Start to Start: two dependent tasks are started simultaneously.
- Start to Finish: when one task is started another dependent task which is in progress is finished.
Task dependency along with the four types can be used in Critical Path project management. A project managed under this methodology is regarded as a series of dependent tasks. Among these tasks there is a set of tasks that have zero float (an amount of time that doesn’t cause a delay for the project). These dependent tasks create a critical path.