The "Content-Disposition" header is used in HTTP responses to indicate how content should be handled by the browser. It can specify whether the content should be displayed inline in the browser or treated as an attachment to be downloaded. This is particularly useful for files like documents or images. When a server sends a file, it can include the "Content-Disposition" header with a value of "attachment" to prompt the user to download the file instead of viewing it directly. This header can also include a filename parameter, which suggests a default name for the downloaded file, enhancing user experience.