1. Data Source: It can be a database, text file, excel spread sheet or an XML file.
2. Data Provider: A set of libraries that is used to communicate with data source. Eg: SQL data provider for SQL, Oracle data provider for Oracle, OLE DB data provider for access, excel or mysql.
3. SQL Connection: It establishes connection.
4. SQL Command: It allows to manipulate database by executing stored procedure or sql statements.
5. SQL DataReader: It provides a forward-only, read-only, connected recordset.
6. DataSet: dataset is a disconnected, in-memory representation of data. It can contain multiple data table from different database.
7. SQL DataAdapter: It populates dataset from data source. It contains a reference to the connection object and opens and closes the connection automatically when reading from or writing to the database.
8. DataView: It provides a means to filter and sort data within a data table.
9. 'Disconnected Data Source': Ado.net makes the connection to the database server only when it needs to do a transaction and disconnects once the transaction is over (similar to an http connection over the internet). This greatly reduces the network traffic.
10. Strongly Typed Dataset Object: Strongly typed Dataset object allows you to create early-bound data retrieval expression. It is faster than late-bound data retrieval expression.