One of the many great benefits of a website is that when times change, it can change with you.

No longer, for example, are companies tied to arbitrary production cycles for product releases. When it’s ready, you start publicising and selling it – you don’t have to wait until your next brochure run. Bang – and it’s on your website.

This is a good thing. With a hidden downside.

While your old product page (or service page, or blog or whatever) has been sat on your website, Google’s hopefully got to know it pretty well. It’s been popping up in search engine results. If you’ve been doing your job properly, it’s gained some inbound links from other websites, so that Google knows the page is popular.

Then, along comes a new product or service. So, you build a newpage, then delete the old one and publish the new one. Seems logical.

The problem is, Google has zero understanding that the new page is in any way related to the old one. You see an updated or new service. Google sees poof! page gone; followed by poof! new page arrives.

What you’ve done is wiped the slate clean. Any search engine value the old page had is now in the bin. The new page has to earn its reputation and ranking afresh. Worse, any links to that page on other websites no longer work, resulting in the dreaded 404 error: page not found. (And many visitors won’t go looking for it either, they see the 404 page as ‘I no longer exist’ and surf off elsewhere.)

There are a few alternatives to working in this way, eachof which issignificantly better for search engines and website visitors.

The first is to consider not binning the page at all, but letting it become an archive page. It will need the addition of some text to point people to the new version of something, but that will speed both Google and your visitors on their way. This can be useful but it needs clear signposting to the new version and just-as-clear labelling to tell people that the page is an archive. If you think that no websites work like this, consider news websites – they leave pages up even as a news story evolves. The same event can be covered by dozens of pages.

The second is to simply change the page, keeping its URL the same. This can be useful where a product is updated to a new version, or even for an annual event. The contents of the page can change but its location and URL are fixed. This is a very good strategy forsection pages of a website – pages which contain subordinates. It can be useful for a service or product page too.

If you really need to remove the page, then there is a process for telling Google that what used to live here, is now permanently moved to here. It’s called a 301 redirect (I know, tech people and their code numbers). Essentially, anyone using the old URL is redirected to the new page seamlessly. It’s something you set up on your Web server. The good thing is that not only do people instantly see the new page, with no hint of the old one, Google does too – and, more importantly, it understands fully the relationship between the old page and the new one. That your newborn page is a direct replacement.

The value of this is that Google will honour any search engine value that the old page had, on the new page. You’re not starting from scratch, the old page has given the new one a leg up.

The value of the 301 redirect doesn’t only apply to new pages which replace old ones.

Consider this. When you move a page on a website, Google has no concept that the page is moved. Google sees poof! page gone; followed by poof! new page arrives. It’s exactly the same search engine own goal as deleting and replacing.

So, when a page is moved to a different place on your website, it’s more than a good idea to implement a 301 redirect. That way people following links still arrive in the right place and Google knows exactly what’s going on.

There’s another and potentially more crippling circumstance where a 301 redirect can save your search engine bacon. Let’s say yourename an important section of your website. One where perhaps lots of products or services are kept. Just a small change, at the top level. You might do this for the best of reasons, perhaps assuming that the change just affects that section/folder.

No – from Google’s perspective it affects every page from that folder down. If it contains a lot of content (products, services, blogs, news, whatever) then any search engine value those pages had is wiped utterly clean. Google does not see a section name change. Google sees poof! 100 pages gone; followed by poof!11 new pages arrive.

In this scenario, a 301 is required for every page that’s affected by the change. Google doesn’t especially mind how many redirects it handles – it will understand that all of those pages are still valid, they’ve just moved. Your search engine rankings for those pages should remain unchanged.

This shouldn’t really be seen as optional. If you’re in any way concerned about where you rank on Google, then this is essential housekeeping. Otherwise, you’re continually working against yourself.