Pattern & practice enterprise library is the set of assembles provided by Microsoft. It is the best approach to doing some task likewise: Caching, Data Access, validation etc.
For example: if you want to CURD operation to the database in the Data Access layer you can use
Microsoft.Practices.EnterpriseLibrary.Data.dll and dlls related to it that provides best way to do this.
You can check the bellow is the link :
http://msdn.microsoft.com/en-us/library/ff650706.aspx[
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