SQL Server is Microsoft's "heavyweight" database management system.  Based on IBM's SQL (Structured Query Language), it features a powerful relational database engine.  Unlike Access, this product is not for the novice user.  It is used for serious applications development requiring simultaneous access to a database by many users.

While Access can easily allow a dozen users to update the database simultaneously, and scores of users to access information at the same time, it was not intended for applications that require considerably more simultaneous access.  Thus, a web site, as an example, which is projected to attract hundreds of simultaneous users, would not use Access.  Rather, the database would be SQL Server.  The actual SQL queries, however, which retrieve and update the data, would be almost identical to the ones used for Access.  We've been using SQL since the 80's...

While we at Corporate Technology pronounce it "sequel", you may also hear it called S-Q-L.