Well, yes and no. You can build an entire website using ASP.net with C# or VB.NET, but ASP.NET dynamically builds HTML, which is the language the browser understands.
In other words, ASP.NET is a server-side process that works in the confines of your web server to dynamically generate HTML documents. The HTML documents are sent to the client browser, which then renders them on that machine.
I hope that helps.