Microsoft SQL Server as a relational database management system designed for storing and retrieving data for various software applications. It outlines the client-server architecture of SQL Server, highlighting three core elements: the Protocol Layer for connectivity, the Relational Engine for query processing, and the Storage Engine for data management. The text further explains the components within each of these layers and briefly discusses some advantages of using SQL Server. Finally, it illustrates how an application interacts with the database server in a typical web environment.