Confronted by a 404 page, they may then attempt to manually correct the URL, click the back button, or even navigate away from your site. As hinted in an earlier post for “Dont’ use soft 404s - File Not Found”, continuing on the 404 series, Google added a new section in Webmaster Tools called “Enhance 404 pages”. If you’re hosting your own website or blog and you can create a custom 404 page.
Google now allows you to embed a widget in your 404 page that helps your visitors find what they're looking for by providing suggestions based on the incorrect URL. In addition to attempting to correct the URL, the 404 widget also suggests the following, if available — “a link to the parent subdirectory, a sitemap webpage, site search query suggestions and search box”.