What is LINQ to SQL?
LINQ to SQL is a specific LINQ implementation for SQL Server. LINQ to SQL converts LINQ queries written in C# or Visual Basic into dynamic SQL, execute it on the server and marshal the results in return. LINQ to SQL also supports making changes to the returned objects and applying those updates back to the database. These updates can be applied by the LINQ framework using dynamic SQL or Stored Procedures. See: LINQ to SQL main page, and LINQ to SQL 5 minute overview.