What is tracker workflow?

To help users handle their tracker items effectively, you can set up some workflow rules. Workflow rules require a user to do something to a tracker before they can reassign it or update its status.

Administrators can define these kinds of workflow rules:

Status transitions that a user can make based on an artifact's current status.
For example, if an artifact is Open, you can specify that it can be changed to Pending or Cannot Reproduce, but not to Closed.
Status transitions that a user can make based on his or her role.
For example, if an artifact is Pending, you can specify that only users with the role QA Engineer can change it to Closed.
Field values that a user must provide when making a specific status change.
For example, if an artifact is Closed, you can specify that a user must enter a comment in the Comments field before changing the artifact's status to Open. You can also require an attachment.

You can create a workflow for each combination of tracker status values in a tracker.