LINQ to SQL is an ORM tool that connects to SQL Server
databases. It generates business objects to match a database's table
structures, which are all centrally available through the DataContext class. The
LINQ-to-SQL designer creates a custom DataContext class that contains a series
of Table<Entity> objects representing each of the tables in your
database.
LINQ to SQL makes it easier to create application architecture,
with some caveats (what doesn't have any in life?).