ActiveX Data Objects (ADO) is a Microsoft technology that allows developers to access and manipulate data from various sources, such as databases and spreadsheets. It provides a set of COM (Component Object Model) objects that simplify the process of connecting to data sources, executing commands, and retrieving results. ADO is commonly used in applications built with Visual Basic and ASP.NET, enabling seamless interaction with databases like SQL Server and Oracle. By using ADO, developers can write code that is more efficient and easier to maintain, as it abstracts many complexities involved in data access.