Task dependencies in project management describe how tasks are related to one another and in which order they should be completed. Properly managing these dependencies is key to keeping a project on track and ensuring its successful completion.
On a Gantt chart, dependencies are depicted with orange arrows.
Once you add a new task, hover over its bar on a Gantt chart. You will see little circles at each end of it. To set task dependencies, just connect those circles according to the type of the dependency you need.
There are 4 different types of dependencies:
1 Finish to Start (FS) means that task B (successor) can’t start before task A (predecessor) finishes.
Example: in a software development project, developers start coding a feature only after the feature requirements have been elaborated and approved.
2 Finish to Finish (FF) means that task B can’t be finished before task A finishes.
Example: in a construction project, the construction part finishes once both the interior and exterior are fully completed.
3 Start to Start (SS) means that task B (successor) can only start after task A (predecessor) has started.
Example: in a product development project, prototype development can start once the concept ideation task starts.
4 Start to Finish (SF) means that task B can only be finished once task A has started.
Example: in a project involving migration to another IT system, the old system that has been used can be only deactivated once the new solution has been put into action.
Note that if you increase or decrease the amount of time for a task with dependencies, all the other tasks it is connected to, will also move on a timeline. In that case, you will also see the indication of the completion delay for all the connected tasks.