Working with ASP.NET sites
ASP.NET web pages enable you to create dynamic content for your site. With a static HTML page (.htm or .html file), the server fulfills a web request by reading the file and sending it as-is to the browser. In contrast, when someone requests an ASP.NET web page (.aspx file), the page runs as a program on the web server. While the page is running, it can perform any task that your site requires, including calculating values, reading or writing database information, or calling other programs. As its output, the page dynamically produces markup (elements in HTML or another markup language) and sends this dynamic output to the browser.
You must have the Microsoft .NET Framework Version 2.0 Redistributable Package installed on your computer to work with ASP.NET controls in Microsoft Expression Web. You can download the .NET Framework at the Microsoft Download Center. You must also be working on a site that resides on a server that has ASP.NET 2.0 installed.
Expression Web allows you to add any ASP.NET control to an .aspx page and set properties that determine behavior and appearance. You can use all the Expression Web style, formatting, and design tools with the ASP.NET controls.
Expression Web allows you to open and design sites created in Microsoft Visual Studio 2005 or in Microsoft Visual Web Developer Express Edition. Similarly, both Visual Studio and Visual Web Developer Express can open and modify Expression Web sites. A typical scenario for web development is that a designer uses Expression Web to create the look and feel of a site, including the layout of ASP.NET pages with ASP.NET controls. A developer then opens the page in Visual Studio 2005 or Visual Web Developer Express Edition and adds the page's code.
You can also write inline code for ASP.NET controls in Expression Web. (A small example is shown below.) However, you have a much greater range of debugging and coding tools in Visual Studio 2005 and Visual Web Developer Express. For example, you can create code behind files for ASP.NET controls in Visual Studio 2005. For the best design and development experience, design the pages in Expression Web and then code and debug them in Visual Studio .NET 2005 or Visual Web Developer.