ASP.NET is a web application framework developed and marketed by Microsoft to allow programmers to build dynamic web sites, web applications and web services. It was first released in January 2002 with version 1.0 of the .NET Framework, and is the successor to Microsoft's Active Server Pages (ASP) technology. ASP.NET is built on the Common Language Runtime (CLR), allowing programmers to write ASP.NET code using any supported .NET language. ASP.NET is a stable and mature platform for building rich and powerful Web applications, so it's hard to imagine a new set of compelling features being added to it.
With ASP.NET 4.0, Web Forms controls now render clean, semantically correct, and CSS friendly HTML markup. Built-in URL routing functionality allows you to expose clean, search engine friendly, URLs and increase the traffic to your Website. ViewState within applications is smaller and can now be more easily controlled. And more controls, including rich charting and data controls, are now built-into ASP.NET 4.0 and enable you to build applications even faster.
Visual Studio 2010 makes it easier to edit, search, and navigate code. Improved VB and C# Intellisense makes it even easier to find and use classes within the .NET Framework. Improved JavaScript IntelliSense enables better AJAX development. New code navigation and visualization features enable you to quickly find and navigate large projects and visualize dependencies across your code-base. Improved unit testing, debugging and profiling help support building robust applications.
In parallel, Microsoft developed a brand-new, alternative programming model called ASP.NET MVC. Unlike the classic Web Forms model, ASP.NET MVC helps developers create Web applications in accordance with a widely recognized design pattern: the Model View Controller.Today, the overall ASP.NET platform is made up of a few distinct components: Web Forms, ASP.NET MVC, Dynamic Data controls and ASP.NET AJAX. ASP.NET 4.0 platform provides further refinement in the areas of Web Forms, Dynamic Data controls and, last but not least, ASP.NET AJAX.
Visual Studio supports different programming languages by means of language services, which allow the code editor and debugger to support nearly any programming language, provided a language-specific service exists. Built-in languages include C/C++ (via Visual C++), VB.NET (via Visual Basic .NET), C# (via Visual C#), and F# (as of Visual Studio 2010). Support for other languages such as M, Python, and Ruby among others is available via language services installed separately. It also supports XML/XSLT, HTML/XHTML, JavaScript and CSS.
Improved Performance and Scalability
ASP.NET automatically detects any change, dynamically compiles files if needed, and stores the compiled results to reuse for subsequent requests. Dynamic compilation ensures that your application is always up to date, and compiled execution makes it fast.
Rich Output Caching : ASP.NET output caching can dramatically improve the performance and scalability of your application. When output caching is enabled on a page, ASP.NET executes the page once and saves the result in memory before sending it to the user.
Enhanced Reliability
Memory Leak, Dead Lock, and Crash Protection: ASP.NET automatically detects and recovers from errors such as dead locks and memory leaks to ensure that your application is always available. For example, when a memory leak is detected, ASP.NET automatically starts up a new copy of the ASP.NET worker process and directs all new requests to the new process. After the old process has finished processing pending requests, it is gracefully disposed of and the leaked memory is released.
Easy Deployment
With ASP.NET you can deploy an entire application by copying it to the server. Configuration settings are stored in an XML file within the application.
ASP.NET lets you update compiled components without restarting the Web server.
New Application Models
XML Web services allow applications to communicate and share data over the Internet, regardless of operating system or programming language. ASP.NET makes exposing and calling XML Web services simple.
Developer Productivity
Easy Programming Model : ASP.NET makes building real-world Web applications dramatically easier with server controls that let you build great pages with far less code than classic ASP.
Rich Class Framework : The .NET Framework class library offers over 4,500 classes that encapsulate rich functionality such as XML, data access, file upload, regular expressions, image generation, performance monitoring and logging, transactions, message queuing, and SMTP mail.