Adding this web part to a document causes it to return a custom HTTP response when the page is requested. The response is only generated on the live site.
For example, the web part can be used to create a page that provides a robots.txt response for web crawlers, as described in
Developer's Guide -> Development -> Page processing and URLs -> Search engine optimization -> Managing robots.txt.
Help URL: http://devnet.kentico.com/docs/webparts/index.html?CustomResponse_overview.htm