Every URL that's ever earned a backlink, ranked for a keyword, or built up trust represents real accumulated value — and that value is fragile the moment the URL changes. A site redesign, a URL restructure, or a simple typo fix can wipe out years of earned authority if it's not handled correctly. A 301 redirect is what prevents that.
What a 301 Redirect Actually Does
A 301 is a permanent redirect — it tells both browsers and search engines that a page has moved for good, and that whatever authority the old URL had should transfer to the new one. It's different from a 302 (temporary redirect), which tells search engines the move isn't permanent and authority shouldn't fully transfer — a distinction that trips up a lot of migrations.
Situations that call for a 301:
- A page's URL changes as part of a redesign or restructure
- A product is discontinued and should point to its closest current replacement
- Consolidating two similar pages into one, stronger page
- Fixing www vs. non-www or http vs. https inconsistencies
A Simple Framework
- Before changing any URL, list every old URL that needs to map to a new one
- Redirect each old URL to its closest genuinely relevant replacement — never default everything to the homepage
- Use 301s specifically for permanent changes; reserve 302s for genuinely temporary situations
- After launch, crawl the site to confirm there are no redirect chains (A to B to C) or loops
> Tip: A redirect chain — where an old URL redirects to another redirect, which redirects again — slows crawling and can quietly leak authority at each hop. Always redirect straight to the final destination.
Common Mistakes
- Mass-redirecting every old URL to the homepage instead of a relevant replacement
- Using a 302 for what's actually a permanent move
- Leaving redirect chains in place after a series of site changes over time
- Forgetting to update internal links to point directly to the new URL instead of relying on the redirect indefinitely
A redirect generator simplifies building the correct rule syntax, and a broken links finder afterward confirms nothing was missed in the migration.
Redirects are one of the least visible parts of an SEO migration and one of the most consequential — get them right and years of earned authority moves with the site; get them wrong and it simply evaporates.