Codebehind

Codebehind is a programming concept used in web development, particularly in the context of ASP.NET. It refers to the practice of separating the user interface (UI) code from the business logic code in a web application. This separation is achieved by using a codebehind file, which is a separate file that contains the server-side code for a web page.

The codebehind file is typically written in a programming language such as C# or VB.NET, and it is associated with a corresponding markup file, usually an ASPX file. The markup file contains the HTML and other UI elements, while the codebehind file contains the code that handles events, processes data, and performs other business logic tasks.

The use of codebehind promotes a clean and organized code structure, making it easier to maintain and update the application. It also allows developers to focus on different aspects of the application simultaneously, with one team member working on the UI and another on the business logic.

In ASP.NET, the codebehind file is linked to the markup file through a directive at the top of the markup file. This directive specifies the language of the codebehind file and the path to the file. When a user requests a web page, the ASP.NET runtime compiles the codebehind file and executes the code, generating the final HTML that is sent to the user's browser.

Overall, codebehind is a fundamental concept in ASP.NET development that helps to create well-structured, maintainable, and scalable web applications.