SQL Server 2008 Express is a free edition of SQL Server that is an ideal data platform for learning and building desktop and small server applications, and for redistribution by ISVs.
Microsoft SQL Server 2008 Express is a powerful and reliable data management system that delivers a rich set of features, data protection, and performance for embedded application clients, light Web applications, and local data stores.
It is a version of Microsoft's SQL Server relational database management system that is free to download or distribute. It comprises a database specifically targeted for embedded and smaller-scale applications. The product traces its roots to the Microsoft Database Engine (MSDE) product, which was shipped with SQL Server 2000. The 'Express' branding has been used since the release of SQL Server 2005.