A PostBack happens when a user takes some action (like submitting a form) that sends information from the page to the server for processing via POST method.

In ASP.NET, “PostBack” refers to the process by which a form is submitted to the server for processing. When a user interacts with a web page, such as clicking a button or selecting an option in a dropdown list, a PostBack occurs. This triggers an HTTP POST request to the server, which processes the form data and generates a response that is sent back to the client.

During a PostBack, the entire page is usually posted back to the server, including view state data, which allows ASP.NET to maintain the state of controls on the page between PostBacks. This enables the web application to provide a rich, interactive user experience.

In summary, “PostBack” in ASP.NET refers to the process of submitting a form to the server for processing, typically triggered by user actions, such as button clicks, and it plays a crucial role in enabling interactive web applications.