Why do I need to put the requirements into categories?

Categorizing the requirements will help you stay organized, as you gather, manage, and add new requirements. It will save time, reduce the odds of missing requirements, and help you ensure that the right stakeholders review the right requirements. Of course, the categories will change from project to project and solution to solution, so enlist your business and technical partners to help you discover the best sets of categories for the present needs.

A common place to start is with the broadest categories: the functional requirements, nonfunctional or business requirements, user requirements, and system requirements. You might consider letting the project methodology drive some of the requirements categories. Context diagrams and similar tools can help you sift the requirements into categories, based on how they contribute to the business or system solution. For data-centric work, a data dictionary might help you choose a categorization strategy based on the data nomenclature. Depending on your categorization scheme, you may find that traceability tools will also help ease the categorizing process.