ADO.NET is a set of computer software components that programmers can use to access data and data services. In simple words, ADO.Net is an object-oriented set of libraries that allows you to interact with data sources. Commonly, the data source is a database, but it could also be a text file, an Excel spread sheet, or an XML file. It provides steady access to data sources such as Microsoft SQL Server, as well as data sources using OLE DB and XML. Data-sharing consumer applications can use ADO.NET to connect to these data sources and retrieve, manipulate, and update data. It is a part of the base class library that is included with the Microsoft .NET Framework. It is commonly used by programmers to access and modify data stored in relational database systems, though it can also access data in non-relational sources.
ADO.NET is the .NET technology for interacting with data sources. There are several Data Providers, which allow you to communicate with different data sources, depending on the protocols they use or what the database is. Irrespective of the Data Provider used, programmers can use a similar set of objects to interact with a data source. The SQL Connection object lets you manage a connection to a data source. The SQL Command objects allow you to interact with the data source and send commands to it.
ADO.NET includes .NET Framework data providers for connecting to a database, executing commands, and retrieving results. Those results are either processed directly, or placed in an ADO.NET DataSet object in order to be exposed to the user in an ad-hoc manner, combined with data from multiple sources, or remoted between tiers. The ADO.NET DataSet object can also be used independently of a .NET Framework data provider to manage data local to the application or sourced from XML.