What a 301 does
A redirect is an instruction from your server: this address now lives over there. The 301 status code means permanent. Search engines generally pass most ranking signals to the new address over time and replace the old address in results. A 302 means temporary, used when the original will return.
When you need one
Use 301s when you change a page's web address, merge two pages, move to a new domain, switch from http to https, choose between www and non-www, or delete a page that has a close replacement. A redesign without a redirect map is the most common cause of lost traffic after a relaunch.
Redirect to the most relevant page. Sending every old address to the home page confuses visitors and may be treated by search engines as a soft not found.
Building a redirect map
List old addresses in one column and the closest-matching new address in the next. Pull the old list from your sitemap, analytics and a site crawl. Check Search Console for pages that get clicks. Prioritize pages with links and traffic.
Keep a spreadsheet so you can verify each one after launch and recheck later.
How to set them up
On WordPress, SEO or redirect plugins offer a simple form. On hosted builders, there is usually a URL redirects area in settings. On Apache servers, rules go into the .htaccess file, and on Nginx into server configuration. Be careful with syntax, because one wrong character can take down the whole site.
Make redirects direct. Old A should go straight to final C, not through B first.
Test and maintain
Visit several old addresses and confirm they land on the right page with a single hop. A crawling tool can check the whole list and show status codes. Keep redirects in place for a long time, ideally a year or more, as links from other sites persist.
Update internal links to point straight to the new address instead of relying on the redirect. That is faster for visitors and cleaner for crawlers.
Redirect chains and loops to avoid
After several redesigns, you might have page A redirecting to B, which redirects to C. This chain slows loading and can lose crawl efficiency. A loop, where two rules send visitors back and forth, produces an error page. Both usually arise when new rules are added without checking old ones.
Review your redirect list when you add rules, and flatten chains so each old address goes straight to its final destination.
Also watch for redirects that mix http and https or www and non-www in awkward orders. A tidy chain has exactly one hop, and a crawler report that lists redirect counts will quickly reveal the ones that need repair. Fix the highest-traffic pages first, then work down the list.
Common questions
Do redirects lose SEO value?
Search engines say properly implemented redirects pass signals, but a changed page may still see temporary fluctuation.
301 or 302?
Use 301 for permanent moves. Use 302 only when the change is truly temporary.
How long should I keep a redirect?
At least a year. If the old address still gets visits or backlinks, keep it indefinitely.
This guide is general information. Search engines change how they work and their guidelines; check Google's current documentation for your situation. Nobody can guarantee a ranking.