Introduction to Server Controls You do not need to specify the Html to be output from the server-side code as ASP.NET provides you the Server Controls that specify the functionality which you want to see in the browser and ASP.NET will decide the output which has been sending to the browser.when a request comes in,ASP.NET examines the request to see which browser type is making the request as well as the version of the browser, and then it produces HTML output specific to that browser.
ASP.NET provides two distinct types of server controls
1. HTML Server controls
2. Web Server controls
If you are thinking which server control is better so it depends only on what you are trying to achieve.
HTML server controls represents the HTML elements.For example if you place an HtmlTable server control on the ASP.NET page then it will work automatically with a <table> element. On the other hand, web server controls represents to specific functionality that you want on your ASP.NET pages. This means an <asp: Panel> control might use a <table& or another element altogether — it depends on the capability of the browser making the request.