HTML Elements vs. WebControls?

What are the pros and cons to using each?

For example, why should I use the asp.net textbox instead of the HTML element textbox?

This has been confusing me for awhile now.

Thanks for any input.

JamesHTML server controls
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HTML elements exposed to the server so you can program them. HTML server controls expose an object model that maps very closely to the HTML elements that they render.

Web server controls
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Controls with more built-in features than HTML server controls. Web server controls include not only form-type controls such as buttons and text boxes, but also special-purpose controls such as a calendar. Web server controls are more abstract than HTML server controls in that their object model does not necessarily reflect HTML syntax
Web Server controls require more overhead... if you are concern about performance then I woud go with Html server controls. (Not a huge difference though...)