A traceability matrix traces requirements to tests, code, and design specifications. It provides backward traceability from tests to requirements and forward traceability from requirements to tests and code. The matrix links high-level requirements to lower-level tests, design documents, and code files. This allows one to ensure all requirements are tested, identify untested requirements, and determine which tests need updating when requirements change.

1. Traceability Matrix
The Traceability Matrix is to be able to trace from top level requirements to
implementation, and from top level requirements to test. It shows the
relationship between Test Requirements and Test Cases.
Using Traceability Matrix, we can check that which requirements are covered
in which
Test cases and which test case covers which requirements. The same apply
for the code too means which codes are covered which requirements and
which requirements are covered in which section of the code too.
They are types of traceability matrix:
1. Forward traceability
2. Backward traceability
3. Bidirectional traceability
1. Forward Traceability:

2. Mapping takes place from requirements to test cases
2. Backward Traceability:
Mapping takes place from test cases to requirements.
Bidirectional Traceability:

3. It contain Forward and backward traceability .Bidirectional matrix is good for
practise
A traceability matrix is a table that traces a requirement to the tests that are
needed to verify that the requirement is fulfilled. A good traceability matrix
will provide backward and forward traceability,. The matrix links higher level
requirements, design specifications, test requirements, and code files. This is
also known as Requirements Traceability Matrix or RTM.
In RTM each requirements should be traceable: Written test cases should be
traceable to its requirement specification. If there is new version then
updated test cases should be traceable with that.
and make sure that all requirements included in the test cases
It Easy to identify the missing functionality.
If there is a change request for a requirement, then we can easily find out
which test cases need to update.

4. It is also use for the test coverage.