Core Class Library
The core class library reference of Microsoft SharePoint Foundation includes the major public namespaces that are usable by third-party developers for solutions that run on servers (as distinct from running on a client) and that provide functionality primarily for end-users and low-level administrators such as site owners. (For higher level administrative functionality, see the Administrative class library reference. For classes that run on a client, see the Client API library reference.)
Provides classes, interfaces, and structures for working with site collections, Web sites, lists, and list items.
Provides the classes that implement the LINQ to SharePoint provider.
Provides classes that enable extension and customization of Meetings Web sites.