title: What is the use of a persistence layer in any application?
body: <p>I have to create an application in which I am asked to create an persistence layer in the application. The application is in .net. I have created a business layer and a presentation layer but I don't know how and why I should create a persistence layer.</p>
  
  <p>I googled and came to know that persistence layer is used for storing and retrieving data usually from a database.</p>
  
  <p>Can anybody explain in detail?</p>