For most of the work done with data in ADO.NET, you don't have to delve deeply into schemas. When you use the tools to create a DataSet representing tables in your database, Visual Studio .NET generates an XML Schema describing the structure of the DataSet. The XML Schema is then used to generate a typed DataSet, in which data elements (tables, columns, and so on) are available as first-class members.
However, there are times when we have to create or edit schemas ourselves. A typical example is developing a schema in conjunction with a partner or client. One will often have to map the schema elements to the structure of one's own database. VB provides us with visual tools for working with XML files/schemas/ADO.NET Datasets. It's called the XML Designer. The XML Designer is used to create and edit XML Schema files, ADO.NET Datasets, XML data files, and XML source code. The XML Designer has three views.