Whereas the use-case is a convenient packaging of analyzed requirements, the design is a convenient packaging of implementation details for the various parts of a use-case. A requirement captures the what. A use-case captures the where, who, which, and when. A design captures the how. The impact of a design describes what impact that this solution has on the overall system. A high-level description of database schema changes usually goes here. Each detail of a design references the relevant use case part, the software asset to be affected, and instructions on how to change that asset in order to implement the approved functionality. Designs also come with a lot of standard features.