Whenever we create an enterprise level apllications then we break the entire architecture into different layes like UI (user interface) layer, Entities (containing plain classes)Layer, DAL(Data access layer) and Service layer. Now, as u asked, all the data base related logic like-- 1> to access database 2> to perform CRUD operations 3> to create instance of database objects. All these logics are written in data access layer for the purpose of seperation of concerns and to provide more robust and neater code. :) :) please have a look at these articles..... Creating ASP.NET Applications with N-Tier Architecture[^] http://www.codeproject.com/Articles/36847/Three-Layer-Architecture-in-C-NET