Traceability Matrix

Traceability Matrix is more likely an excel sheet(Table) that is used for mapping Requirements against test cases. This process is done to make sure that all the requirements have been covered in test cases. This can also be used to correlate any two documents(such as HLDD VS LLDD, LLDD VS Test Plan, Test Plan VS Test Cases)  that have a many-many relationship.

In a real time environment, normally once the test cases are completed by QA team, there would be a Peer review session where QA 1's test cases would be reviewed by QA 2 and QA 2's test cases would be reviewed by QA3 and QA3's by QA1. In spite of these peer reviews there would be cases where some of the requirements weren't covered in test cases. So to overcome this scenario, Traceability Matrix sheet is used for checking.

Generally in FRS document, each requirement would have an required number which is called as Requirement ID.In the same way each test case would have a Test case ID. Now in Traceability Matrix sheet(or Table), user would enter a Requirement ID in each cell horizontally. In the same way User would enter Test case IDs in each cell vertically. Once all Requirements IDs and Test case IDs are entered by the user, they would start mapping each test case against a requirement. Meaning a 'X' symbol would be placed in the cell that intersects the test case and Requirement. A requirement might have multiple X symbols indicating that there are multiple test cases for that requirement. Also there might be cases where a single test case is mapped with multiple requirements. Once the mapping process is complete, we can go through each requirement cells and see if anything doesn't have an X symbol. If anything doesn't have an X symbol, it means that there is no test case written for that requirement.