- Web User Controls are files with the .ascx extension that can be included in Web Forms, with the parent Web Form becoming the container of the control. Web User Controls allow you to easily reuse pieces of functionality in a number of Web Forms.
- Web User Controls are files with the .ascx extension that have a structure similar to the structure of Web Forms, but they can't be requested directly by a client web browser; instead, they are meant to be included in Web Forms or other Web User Controls.