No one intends to make a mistake on the web, but sometimes we miss something and 404 errors happen. What is a 404? It's an error that is shown to the user when a server is unable to deliver a certain page to them. You've seen them before; they're usually a cause for frustration, and the realization that you're not as close to your content or page as you thought you were.
What many people don't understand is how much of an impact a 404 error can have on your overall site performance.
How Are 404s Caused?
Speaking from personal experience, I managed to rack up a number of 404s when I decided to alter the URLs of a site so as to include some top ranking keywords. Not my finest moment, admittedly, and perhaps the cause of said site not gaining any PageRank in its earlier months. The original pages had already been crawled and indexed by Google, so according to the search engines, they existed. But when the URLs were typed in, they didn't, and the original page content was replaced with a delightful 404 error.
Picking Up 404s
So how do you know if your site - which may have multiple pages - has any 404 errors floating around? Google Webmaster Tools will tell your straight away how many pages are pulling up crawl errors and which URLs are causing them, but you can also pick them up by plugging your domain name into tools such as Xenu Link Sleuth or Screaming Frog. These display all the URLs within your domain and the status code for each one; 200 being in full working order and 404 being the ones you need to look out for and fix.
Fixing them is fairly simple. The best way to do it is to redirect the old broken URLs to an existing, relevant URL using a 301 (permanent) redirect. Your web master or developer can do it for you, or if you work on a CMS, you can get a plugin to do it for you. Not only will this streamline your user's experience, but it will also allow any potential page authority to pass from the broken URL to the new, relevant page.
Another solution is to create a custom 404 page that will still display when the user encounters that error, but it can have a link pointing back to the home page or any other page for that matter.
Who Knew 404s Could Be So Much Fun?
We trawled some great online resources and found this collection of really creative 404 pages. Most people don't think to have a little fun with these, as an error is seen in such a negative light, but look at the crazy, awesome ideas that people have played on to make light of the situation.
There are so many more with videos and interactive games to play. Some of them are so brilliant, you'll almost forget what you were searching for in the first place.
Go ahead, find your 404 errors - if you have any - and have some fun with them. It's pretty much guaranteed that you'll create a memorable experience for your users... even if it's in error.