Is a 404 error bad for SEO?

A handful of 404s is normal and harmless. It hurts when pages that earn traffic or inbound links go dead without a redirect, because the ranking value of that URL is lost.

What is the difference between a 404 and a 301?

A 404 says the page does not exist. A 301 says the page permanently moved and sends the visitor and the search engine to the new address, carrying most of the ranking value with it.

Should I redirect every 404 to the homepage?

No. Redirect to the closest matching page. Bulk redirects to the homepage confuse visitors and are often treated as soft 404s by search engines.

SEO

404 error

The status code a server returns when the requested URL does not exist on that site.

also called: 404, page not found, http 404

// definition

A 404 error is the response a web server sends when a browser or crawler asks for an address that the server cannot find. Think of it like knocking on an apartment door after the tenant moved out and left no forwarding address. The building (your domain) is still there and answering, but the specific unit (the page) is not. The number itself comes from the HTTP status code family: codes in the 400 range mean the request had a problem on the client side, and 404 specifically means "not found". A 404 is different from a server error (500), which means the site itself broke, and different from a redirect (301 or 302), which means the page moved and the server is pointing you somewhere new.

// why it matters

Occasional 404s are normal on any site that has been publishing for years. They become a problem when links people actually follow, or links other sites point at, land on a dead page. Visitors bounce, search engines drop the URL from the index, and any authority earned by inbound links to that address is wasted unless the old path is redirected to the closest living page. A helpful 404 page that recommends real content, exposes the menu and offers a way to contact a human keeps a lost visitor on the site instead of sending them back to search.

// example

A blog post published at /blog/ai-audit-tips is later renamed to /blog/ai-search-audit-tips. Without a redirect rule, every old link now returns a 404 error. Adding a 301 redirect from the old path to the new one preserves the traffic and the link value.

Questions and Answers

Is a 404 error bad for SEO?: A handful of 404s is normal and harmless. It hurts when pages that earn traffic or inbound links go dead without a redirect, because the ranking value of that URL is lost.
What is the difference between a 404 and a 301?: A 404 says the page does not exist. A 301 says the page permanently moved and sends the visitor and the search engine to the new address, carrying most of the ranking value with it.
Should I redirect every 404 to the homepage?: No. Redirect to the closest matching page. Bulk redirects to the homepage confuse visitors and are often treated as soft 404s by search engines.