There are a handful of ways that people typically categorize/organize their Tasks:
- Group tasks by User Story. This is done by linking the WI's, and this information will show up in WI Queries, and on the Task Board (task board only available in tfs 2012 and up).
- Use the Area field and Area hierarchy to categorize your Tasks. The Area hierarchy is typically used to represent a functional breakdown of your application, then applied to WI's to categorize them based on which functional area they affect.
- Activity Field. There is a field on Task work items called Activity that by default that has the values: Deployment, Design, Development, Documentation, Testing, Requirements. This list can be customized by editing the Work Item Type Definition.