What is ASP.NET?

If research the definition of ASP.NET, you will most likely get the "ASP.NET is a web application framework..." on a lot of web pages. What that basically means is that somebody out there wrote a bunch of code and software that you don't have to write to make programs that run in your browser over the Internet. Pretty cool, I know.

There are other similar things to ASP.NET, most notably Adobe's ColdFusion product. The difference is ASP.NET is based off of Microsoft's Common Language Runtime (CLR), meaning that you can build an ASP.NET website using any .NET Framework supported language, like VB.NET and C# and other products generally only allow one programming language for the web application's functionality.

The structure of an ASP.NET web application is pretty straightforward. Each web form, or piece of your web application, contains two parts: the interface, or the website the user interacts with and a 'code-behind' page, which contains the source code that offers the website's functionality. The interface file is usually just controls and HTML to design the layout and structure of your web application, almost exactly like making websites with HTML and CSS. These files are saved with the ".aspx" extension. The code-behind page is a code module that sits 'behind' the .aspx file (interface) and provides the code functionality for the .aspx page, usually with the extention ".aspx.cs" for C# or ".aspx.vb" for VB.NET.

This is all fine and good, but doesn't mean much if you really have no idea of what is going on behind the scenes. If you are reading this blog, I'm sure you know about web servers, or maybe you don't, so I'll explain it (or try to). ASP.NET web applications exist on a web server that is running software that makes your ASP.NET web application available to users on the Internet, or on your local area network (LAN). The web server contains all the files necessary for your web application: all of the interface files (.aspx) and all of the code behind files that make your application work. When someone goes to your website from their browser, a request is sent to the web server. The web server processes the request and sends the results back to your browser. The request could have been to sign in, sign out, submit a comment or anything else that your web application can handle. A good example of a request is when you want to view information from a database. The web server handles the connections to the database and returns the result as HTML to your web browser. With this model, HTML files are generally the only thing sent back to your web browser. This means the code for your website is never sent to the user's web browser and is kept safely on the web server, provided your web server has security systems in place.

For more technical information on web servers and ASP.NET, please visit the following websites:
http://www.asp.net/ - The Official Microsoft ASP.NET Site
http://en.wikipedia.org/wiki/Web_server - Web server - Wikipedia, the free encyclopedia