Usercontrols can be understood as a portion of web page created separately as some other page but can be called at any location withing a web page. The advantage of creating usercontrol in an application is that you need not to write the same code again and again.
Adding usercontrol to website :
Add usercontrol by simply adding new item to your site as shown in image :
Adding usercontrol to a page :
To add a usercontrol to a page you need to write this code on top :
<%@ Register
src="~/usercontrol/mainheader.ascx"
TagName="UserInformation"
TagPrefix="UserInformation"
%>
after adding the above code on top of the page, now you just need to place the code on the place you need to add the usercontrol
<UserInformation:UserInformation id="UserInformation"
runat="server"/>
As Simple As That
