Let the 404 be a start, not a finish.
A 404 "page not found" error shows a problem happened when someone tried to reach a web page. This opportunity should be working for your site.
Searchers despise the 404 error page, especially when it comes from clicking what looks like a relevant link in a list of search results. Too often, these 404s come up as an ineffective default page in the browser, leaving the visitor no other real choice but to hit the Back button and try again.
One may end up skeptical of future results from that domain, and you may not realise that your are losing visitors and potential sales.
Google, the most popular search engine, doesn’t want to see this. It not only reduces the value of the destination sites that return a 404 error, but also the quality of Google’s search results. A poorly configured delivery of 404 results may keep an otherwise dead page alive in Google's index, to be found again and again.
It's basic stuff, as commenters on the first of a short series of posts at the Google Webmaster Central blog noted. We have only recently been creating custom error pages for our clients, so it’s important that you check to see if you site has one or not – if not, contact us to arrange for this to be done.
Not all 404s are created equal, as Maile Ohye said at the blog today. A 404 could be a soft error or a hard one.
The soft 404 response is the undesirable result. This happens when someone tries to visit a nonexistent URL on a site. Instead of an error page, the website returns a 200 response code and sends the request to the site's homepage.
On the user's side, the person who encountered this probably questioned the sanity of allowing this useless result to happen. It's not a good way to earn repeat visits.
Give the visitor a real 404 page not found result, Ohye said. It's a clear indication both to human and automated visitors about the status of the page.
Google made a week of the 404, and we've got a pretty good idea of where they are going judging by Ohye's comment about sending a helpful "Not found" message to the viewer. Remember that we have the ability to deliver any kind of page in response to a 404 situation, so talk to us now.
A custom 404 error page could let the visitor know that, while the page they wanted isn't there, other pages on the site may be exactly what they need. Visit this link on a site we are currently working on, which is live online, but not yet complete. This error page explains that the site isn't yet complete and encourages the visitor by supplying clear contact details.
Check your site, because if it doesn’t have a custom 404 error page, then you could be losing business and as we have only recently been creating a custom error page for the site's we develop, your site may not have one.