It is an application developed by microsoft. It is a technology that enables you to make a website and perform all necessary operations on it. To answer the question "What is ASP.Net?" It is useful to know what ASP is and how it works. ASP, which means "active server pages", is running with IIS. Your browser will be interpreted as HTML in the event that your web site created with ASP programming language can be viewed by any processor. The other name for websites created with ASP is dynamic websites. When visitors come to your web site, visitors can not view your ASP code and it is a very reliable system for your security. Although the asp code can not be displayed, the client will encounter the results interpreted by the browser. The website is usually encoded with HTML. However, the necessity of using more technical programming languages to build interactive sites arises. Asp is a programming language used for servers with the Windows operating system. Although the HTML language can be used in these softwares, using the asp programming language for more complicated websites such as e-commerce will provide both practicality and functionality. Asp can only work with the web server, ie it can not function as a stand-alone program. If we look at the HTML page, we can see the java script code, but it is not possible to display it for asp. It is quite advantageous for webmasters that your code is safe and impossible to get by anyone else. Different script languages are used in Asp. Your asp page has to end with .asp. What is ASP.Net? the answer given in the form of ASP is incorrect. ASP.Net is a much more sophisticated technology than ASP, even though it is perceived as being written in the same way and is considered the same. Because the code is different from ASP. Uses the common language runtime as code. However, the ASP principle is different. It uses the ASPX structure. With this structure it uses, it separates the content which will be seen in the static structure. The most important difference from ASP is that it is not a language, it is a roof. When we ask "What is ASP.Net?" We get a roof response generated from web applications. These web pages use one of the ".net" languages when creating web applications. There are design items called "code behind".ASP.Net supports different page features by using these design documents and using programming stuff. In this way, the programmer and the designer can work on the page simultaneously. On the Net, there is advanced session management support. With this feature, membership transactions can be done easily. It is possible to create web application interfaces with Master Page with Theme.