The .NET Framework Data Provider for SQL Server (SqlClient) uses its own protocol to communicate with SQL Server. It is lightweight and performs well because it is optimized to access a SQL Server directly without adding an OLE DB or Open Database Connectivity (ODBC) layer.
The .NET Framework Data Provider for SQL Server classes are located in the System.Data.SqlClient namespace.
The .NET Framework Data Provider for SQL Server supports both local and distributed transactions. For distributed transactions, the .NET Framework Data Provider for SQL Server, by default, automatically enlists in a transaction and obtains transaction details from Windows Component Services or System.Transactions.
The following code example shows how to include the System.Data.SqlClient namespace in your applications.