Are 301 redirects necessary for SEO every time you change the name of a web page?

Question

I noticed in Webmaster Tools that pages on my site that were renamed or deleted many years ago are still coming up listed as not found even though there have never been any links to these pages.

So is it necessary every time you change the name of a page, to keep the old page as a 301 redirect to the new page? Or will Google just figure it out over time?

My site has gone from two websites: www.example.com and a mobile version m.example.com, now merged into just one example.com that works in mobile and desktop.

Answer 1

If you change the URL of a page you only need to implement a 301 redirect if that URL is either indexed by search engines (in order to preserve SEO) and/or the old URL is being linked to (or bookmarked) from other sites/users.

If the old URL has been around for a while then it's very likely that either one or both of the above is true, so a 301 redirect is mandatory most of the time.

Or will Google just figure it out over time?

Google will struggle to "just figure it out" if you don't implement redirects. The old/indexed URLs will no longer exist (404 Not Found) and the new URLs are just that, brand new pages. Other sites that are linking to the old pages are just dead links.

or deleted ...

If a page/URL is genuinely "deleted", ie. it has not "moved" or been renamed, then there is nothing to redirect to and a 404 Not Found response is the correct response in this instance.

now merged into just one example.com ...

Aside: You don't appear to have implemented a canonical www to non-www redirect.

Answer 2

Redirection: It's always a good practice if you change your page from old to new then it is highly recommended you apply 301 permanent redirection.

Google considers several factors to rank a page and if your old page had some ranking or even the age factor, it's worth redirecting.

Even, its worth considering your mobile version of links to redirect to respective new URLs.

If you will not redirect then Google will read the new one but you may not get the ranking weight which you had on the old page.

Answer 3

So is it necessary every time you change the name of a page, to keep the old page as a 301 redirect to the new page? Or will Google just figure it out over time?

It's highly recommended that you apply a 301 redirect from the URLs that are considered outdated to the new current URLs so that everyone can still reach your pages without having to memorize a new URL. Also, a 301 redirect saves you the need to advertise new URLs when people already have your old URLs. It is especially important to use 301 redirects for your past visitors that decided to bookmark your old URLs in their browser. Without the links to the new URLs, those guests of yours relying on their browser bookmarks to access the page will have trouble doing so.

If at this time, you feel it is impossible to create 301 redirects, then the next best option is to create a 410 error page indicating to search engines that the page no longer exists. Make sure the 410 error page includes a link to at least one of your active pages (preferably your home page) so users don't feel lost. I'd recommend you do this to the 404 error pages as well so that all of your users can easily access your home page in less than three clicks regardless of how badly they spell a URL.