.NET framework data provider includes the following components for data manipulation: 

Connection : Used for connectivity to the data source 

Command : This executes the SQL statements needed to retrieve data, modify data or execute stored procedures. It works with connection object.It requires instance of connection object. 

DataReader : This class is used to retrieve data. DataReader is forward only and read-only object. We cannot modify the data using DataReader. 

DataAdapter : It works as bridge between dataset and data source. DataAdapter uses fill method to load the dataset.