A CASE tool is a software that helps design and implement information systems by organizing system design techniques like data dictionary and entity relationships. It improves consistency and accuracy in database design and helps maintain design integrity. However, it cannot create a database design on its own. The quality of the design depends on the analysis done by the users. CASE tools can generate reports and diagrams following a theoretical model, simplifying the creation of ER diagrams and documenting the contents of an ERD. The chapter discusses the impact of CASE tools on relational models.