Hello tejkrishna,  

Here is a brief answer to your question regarding the purpose of the Requirements Traceability Matrix. 

 'Trace Requirements' is defined as a 'Task' under the Knowledge Area of 'Requirements Life Cycle Management' in the BABOK v3.0. 

The BABOK v3.0 states the purpose of Requirements Traceability 'is to ensure that requirements and designs at different levels are aligned to one another, and to manage the effects of change to one level on related requirements.' According to BABOK v3.0, 'requirements may be traced to other requirements (including goals, objectives, business requirements, stakeholder requirements, solution requirements (functional and non-functional), and transition requirements), solution components, visuals, business rules, and other work products.' 

On projects I have worked on we included the test cases that were linked to the functional / non-functional requirements.

The Requirements Traceability Matrix I have worked on contained in tabular format, the requirements and its relationships to other requirements and artifacts such as test cases, and also captured the life of the requirement from its origin to deployment or retirement (no longer required) and included modifications. Requirements Management tools (beneficial on large projects) or software tools such as excel have typically been used  to capture this information (usually the software is determined by the project / organizational standards). 

Wish you the best,

Rosina