Every broken link is a dead end for a visitor and a negative signal to search engines. Worse, they multiply silently: you rename a page, delete an old post, or change a plugin — and somewhere, three links now point at nothing.
A 404 in your buying path ("Book now", "View pricing") doesn't just lose that click — it makes visitors doubt everything else on the site. Search engines also waste crawl budget on dead URLs and may rank you lower for a poor user experience.
Manually clicking every link works for a 5-page site, once. For anything bigger, use an automated scan that follows your internal links and reports which return errors — and re-run it monthly, because link rot never stops.
If the destination still exists at a new address, update the link or add a 301 redirect (redirects preserve any SEO value the old URL had). If the content is gone for good, remove the link or point it to the closest relevant page — not the homepage, which frustrates users expecting something specific.