301 Redirect

HTTP redirects send a status code alongside a forwarding URL. A 301 code means permanent — the resource at this address has moved and should not be expected to return. Browsers cache it so repeat visitors go directly to the destination. Search engines treat it as a signal to transfer the link authority accumulated by the original URL to the new one. This is why a 301 is the correct redirect for any URL change that is not temporary.

The most common mistake is using a 302 (temporary redirect) where a 301 is appropriate. A 302 does not reliably pass link equity — it signals that the original URL will eventually return, which tells search engines to hold the authority at the source rather than transfer it. Developers often default to 302 because it's slightly simpler to implement, and the difference is invisible to users. The SEO cost is silent and ongoing.

How much authority a 301 passes has been debated for years. Google's current guidance says it passes "most" link equity — deliberately vague. What's clear is that a direct link always passes more than a redirect, and a single 301 passes more than a chain of redirects. For SEO migrations, the 301 chain from old URLs to new URLs is what transfers years of accumulated authority to the new site structure. Failing to implement it correctly is the most common cause of post-migration ranking drops.

Implement redirects at the server level or via CDN configuration, not through JavaScript. Search engines may not execute JavaScript redirects during crawling. Keep redirect targets topically relevant to the original URL — a 301 from a deleted page about content strategy to an unrelated homepage passes less useful equity than a redirect to a topically similar replacement page.