data set is an in memory cache of data retrived from 
datasource.it is major component of Ado.net. data set is a 
collection of data tables.that you can relate to each other 
with data relations. data set can read and write in a XML 
schema.

Data minig some times called as data or knowledge discovery 
it is a process of analyzing data from different 
procepectives and summerizing into useful information.  
information that can be used to increase revenue, cuts 
costs, or both.