All generic classes for data access are contained in the System.Data namespace.

DataSetThe DataSet is a local buffer of tables or a collection of disconnected       records sets.

 A DataTable is used to contain data in tabular form using rows and   columns

DataRow Represents a single record or row in a DataTable.


 Represents a column or field of  a DataTable


 Represents the relationship between different tables in a data set.

Constraint Represents the constraints or limitations that apply to a particular field or column.