This approach is easier and the code is shorter and reliable.
It provides greater compatibility since it is easy to change
Less work for developer to write client script and a server
Page parameters become strongly typed and automatically
You don't have to parse and convert parameters by yourself. In
ASP.NET, parameters passed on URLs are available through Request.QueryString,
only as strings.
No need to look at a target page's code to know how to call it.
No need for separate documentation about ways to call a page.
Page parameters are automatically validated and become strongly
As we don’t to post entire viewstate of the page using Page
Methods we achieve the bandwidth benefits.
Key Points to Remember
The Page Method should be static using the attribute [WebMethod].
The Page Method can be in the code behind file of the page and in
aspx file as well.
The EnablePageMethods property of the script manger should be
marked as “True”.
The call back methods are mandatory to receive the processed
result on the client side.
Page Methods don’t support all the datatypes to return to client.
We can access the Session. Application and Cache variables using