Thus for used base class for some commom reusable methods in every page of my application...
public class BaseClass:System.Web.UI.Page
{
   public string Get         
        
Base is used when you override a method in a derived class but just want to add additional functionality on top of the original functionality
For example:
  // Calling the Area base method:
  public override void Foo() 
  {
     base.Foo(); //Executes the code in the base class
     RunAdditionalProcess(); //Executes additional code
  }