ADO.NET是微软在.NET Framework中负责数据访问的类别库集，它是使用在COM时代奠基的OLE DB技术以及.NET Framework的类别库和编程语言来发展的，它可以让.NET上的任何编程语言能够连接并访问关系数据库与非数据库型数据源（例如XML，Excel或是文本档数据），或是独立出来作为处理应用程序数据的类别对象，其在.NET Framework中的地位是举足轻重，许多人将ADO.NET视为ADO的下一个版本，但其实它是一个全新的架构、产品与概念。

ADO.NET is a set of computer software components that programmers can use to access data and data services from the database. 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 sometimes considered an evolution of ActiveX Data Objects (ADO) technology, but was changed so extensively that it can be considered an entirely new product.