The Connection class is
provided by all standard ADO.NET providers and represents a
connection between your code and a data source. Connections require
resources, so one hallmark of well-written ADO.NET code is that it
opens a connection only when necessary and releases it as soon as
possible. The Connection class is provided in
several provider-specific varieties, including
SqlConnection and
OleDbConnection.
Most of the Connection properties are
informational and can’t be modified directly.
Instead, before opening a connection, you use the
ConnectionString property to set such information
as the location of the data source, the authentication credentials,
and the connection timeout. The Connection class
is also the heart of client-side
transactions with ADO.NET,
connection pooling, and schema tables with the OLE DB provider.