Redirects are managed with the Retour plugin (by nystudio107). It lets you create and manage redirects, and it also tracks 404 (page-not-found) errors so you can fix broken links.
Earlier versions of this manual referenced a different redirect plugin (Dolphiq Redirect). That plugin was replaced by Retour during the Craft 5 upgrade.
A 301 is the server’s way of telling a browser that a page has permanently moved to a new URL; the browser then loads the new location. Use a 301 when a page’s URL changes so existing links and search results keep working. More detail: MDN — 301 Moved Permanently.
/old-page) and the Redirect URL (the new path, e.g. /new-page).Retour’s Dashboard and 404s views list page-not-found hits. Reviewing these regularly is a good way to spot links worth redirecting.