Connections are the starting point to your data access and determine how you connect to the data store. You need to set properties, like ConnectionString, to establish communications to your data store. Here's a brief rundown of connections' key properties and methods.
ConnectionString: (read/write) string used to open a SQL Server database.
ConnectionTimeout: (read) maximum time allowed for a connection attempt.
Database: (read) name of the current (or soon to be) connected database.
DataSource: (read) name of SQL Server instance to connect to.
ServerVersion: (read) string that identifies the version of the connected SQL Server instance.
State: (read) current state of the connection.
BeginTransaction: (overloaded) begins a database transaction.
ChangeDatabase: changes the current database for an open SqlConnection.
Close: closes the connection to the database.
CreateCommand: creates and returns a SqlCommand object associated with the SqlConnection.
Open: opens a database connection with the property settings specified by the ConnectionString.