The UpdatePanel is a component in ASP.NET that allows for partial page updates without requiring a full page refresh. This means that only specific sections of a web page can be updated in response to user actions, improving the user experience by making applications feel more responsive and faster. When using an UpdatePanel, developers can define which controls trigger updates and which parts of the page should be refreshed. This is particularly useful for applications that require frequent data updates, such as forms or dashboards, as it reduces server load and enhances performance by minimizing the amount of data sent over the network.