ArcSDE is a gateway that facilitates managing spatial data in a database management system. ArcSDE allows you to manage geographic information in one of four commercial databases: IBM DB2, IBM Informix, Microsoft SQL Server, and Oracle, as well as being able to serve ESRI's file-based data with ArcSDE for Coverages. ArcSDE serves spatial data to the ArcGIS Desktop (ArcView, ArcEditor, and ArcInfo) and through ArcIMS, as well as other applications and it is the key component in managing a multi-user spatial database.

o Provides the infrastructure required to manage multiple users editing the same spatial database with long transactions, alternate versions, and history.
o Provides the business logic software for not only creating simple geometric data, but also technology for supporting advanced GIS data types such as images, networks, features with integrated topology and shared geometry, and associating these with rules, behavior and other object properties.
o Allows GIS data to be directly maintained in the format of "spatial types" supported by the DBMS vendors (building on their parallel efforts to develop spatial extensions).
o Integrates the spatial (geometric) search capability provided by the DBMS vendors within the ArcGIS client software applications.