One thing we try to do for our clients once every month or two is to check for broken links. You’d be surprised by how often we find new broken links even after we just fixed them all a month ago. Sometimes a page or an image gets deleted and there is still some page on the site referencing it, sometimes a file gets renamed inadvertently, or sometimes and external site being linked to goes out of business. If you edit your site regularly these types of things happen (especially with images).
Another common creator of broken links is using WYSIWYG (What You See Is What You Get) HTML editors. You can remove a link but the href code can still remain. There is nothing actually being linked, but with the code still in place it creates a non-visible broken link. Your visitors won’t find it but the search engines will.
There is a great program that you can use to check for broken links called Xenu Link Sleuth. It ‘s a free download and works magnificently, finding all broken links throughout your site and providing an HTML report which tells you where the broken links are and where they point to. As an added benefit, Xenu will also provide a site map of your site at the end of the report.
So why bother with all of this? Search engines want to provide the best resources in their search results and if your site is not well maintained, then it definitely would not be considered as one of the “best”. Because of that SEs are known to devalue a site slightly if it contains too many broken links. If you want your site to be considered the best for your industry, you have to act like it. Check regularly for broken links and be sure to get them fixed quickly.