What is the purpose of code behind page?

The code-behind page in a web application, particularly in ASP.NET, serves as a separate file that contains the server-side logic for the associated front-end page. This structure helps maintain a clear separation between the presentation layer (HTML/CSS) and the business logic (C# or VB.NET code). The purpose is to enhance code organization, improve maintainability, and enable easier debugging by allowing developers to write and manage the backend functionality independently of the user interface.