Nothing undermines the credibility of a site quite like a link that returns an error message or a blank page. Visitors have very little patience for these types of problems. All but the most rudimentary Web sites contain numerous links, so chances are that your site, too, contains a few dead ends. Whether your links are "internal" (taking visitors to another location within your site) or "external" (taking visitors to another site altogether), they can break for a variety of reasons. Checking links on a continual basis is an important part of performance monitoring, and because it's also one of the simplest and least expensive monitoring processes, there's no reason your customers should ever be derailed as they click through your site.
Check Internal Links Unless your site is a single page, you probably use links as your main navigation tool. You might have links at the top of a page that take the user farther down on the same page, thus preventing excessive scrolling. You also might have links that take users to other pages on your site. Both of these are internal links. There are several ways to prevent internal broken links.
Check External Links The goal of any e-commerce site is "stickiness," the ability to keep visitors on the site for as long as possible. However, most e-commerce sites also link to other sites. They do this for a variety of reasons, such as to provide information helpful to the user in making a buying decision, or to provide value-added services like gift suggestions. And of course, if your site is content-driven, providing external links to additional resources is a huge benefit to your customers and to your business partners. Your good intentions will quickly backfire, however, if those external links are broken.