A broken link occurs when the URL it points to returns an error instead of the intended page. The most common error is a 404 (page not found), but you'll also see 410 (gone), 500 (server error), or timeout failures. For users, clicking a broken link means hitting a dead end. For search engines, it signals poor site maintenance and wastes crawl budget on URLs that deliver nothing. Links break for several reasons. The target page gets deleted without a redirect, the URL structure changes during a site migration, the external site you linked to goes offline, or someone makes a typo when adding the link. Internal broken links are fully under your control and inexcusable on a well-maintained site. External broken links happen naturally over time as the web evolves, but you should still monitor and replace them. The SEO impact depends on scale and context. A few broken external links in old blog posts won't tank your rankings. Hundreds of broken internal links across your main navigation and product pages absolutely will. Google has confirmed that excessive broken links can harm crawl efficiency, meaning the bot might not discover your new or updated content as quickly. Users who encounter broken links also bounce faster and trust your site less. At Ottawa SEO, we catch broken links in three ways. During migrations, we crawl the staging site with Screaming Frog before launch to verify every internal link works and critical old URLs have 301 redirects. For ongoing monitoring, we run monthly crawls on client sites and use Google Search Console to spot 404 errors Google discovers. For external links, we check high-authority pages quarterly since those outbound links affect user experience even if they don't directly hurt rankings. Fix broken internal links immediately with proper 301 redirects to the closest relevant page, or restore the original content if it still has value. For broken external links, replace them with updated sources or remove them entirely if no good alternative exists.