Content that shows up in more than one site is deemed to be duplicate content. It becomes confusing for search engines as they try to decide which version of the content is relevant to incoming queries.
Duplicate content also sends a bad signal to search engines like Google, negatively affecting your search rankings.
Web page redirection may appear a bit like a minefield at first. Canonical tags and 301 redirects are tools that not only help in avoiding duplicate content but which can also improve the user’s online experience.
Knowing the difference between the two and when to use which ensures not just user satisfaction but helps in generating positive search engine results.
Canonical vs. 301 Redirect
Redirect options can, however, prove to be confusing. A canonical tag informs search engines that multiple versions of the same page exist and indicates which version should be taken as the “original version” to be delivered in relevant search results.
On the other hand, a 301 redirect helps search engines and users find content that has been moved to a new URL.
A 301 redirect means that the page content has permanently been moved elsewhere.
This is an HTTP status code sent out by the webserver to communicate to browsers/crawlers and search engines.
It informs them that the original page they are trying to access has been permanently moved to a new webpage.
When you implement this command, eventually you will pass the most of the original page’s link relevance, authority, and ranking power to the new page.
301 Redirect for Users
For managing the permanent and redirection of a web page, the standard has always been to use the 301 HTTP status code. When your browser receives the 301 code, it automatically goes to the new URL.
Unless they notice the URL change in their browser, users are not likely to notice that they have been redirected to a new URL.
Even if the change is spotted, users are unlikely to be affected so long as they get the content they originally wanted.
Therefore, when it comes to keeping users happy, 301 redirects work quite well so long as the redirecting to a URL doesn’t confuse them.
What 301 Redirect Means for the Search Engines
Theoretically, if search engines encounter a URL that has a 301 redirect, they will follow the redirect to where the new URL is located, and then have the old URL de-indexed.
The search engine should, in addition, pass across any juice from the existing URL link to the new link.
However, they are probably not going to pass 100% juice or even the anchor text.
Although Google indicates that a 301 redirect can pass the anchor text, they don’t guarantee that happening.
When to Use a 301 Redirect
You certainly should use 301 redirects when changing your website’s URL or when moving it to a new location.
In a situation like this, you will not want search engines or users to see your old site, particularly if the changes were prompted by structural changes or new website design.
Google has guidelines on how to use 301 when changing your URL or moving to a new location.
You should also consider using a 301 redirect if your website has expired content such as old products, or old terms and conditions which are no longer relevant or when you have new items that are of no use to your users.
Potential Problems with 301
To begin with, it might not even be possible to implement the HTTP status codes. Perhaps you lack FTP access or your web designers probably haven’t told you it’s possible.
Another downside is that sometimes it takes a while for the different search engines to assign or attribute the new page with the search authority of the original page.
The most frequent common problem associated with a 301 redirect is being incorrectly used.
It’s not uncommon to see people developing an entirely new site and then using a 301 to direct all the original site’s pages to the new website’s homepage. The intention of the 301 was not that.
A canonical tag is also known as a canonical link or rel=canonical. At times, a page comes with multiple associated URLs, so the search engine bot finds it difficult to identify which is the main URL.
The canonical tag comes to resolve the confusion by picking one URL as the main URL.
All the other URLs are deemed as copied versions of the original and they redirect a visitor to the main URL.
When to Use a Canonical
You may want to use canonical when your website generates temporary URLs for the same item or product.
Other scenarios are when your blog system is automatically generating multiple URLs whenever you post a single post under multiple sections or categories or when you have lots of syndicated content.
If your e-commerce site has lots of products, you could end up with several pages showing similar merchandise, for example, red shirt with logo vs. blue shirt with logo. A canonical tag may help to differentiate between the two.
Potential Problems with Canonical
A major problem with rel=canonical is the possibility of misuse during implementation. It’s not a directive which means that it can be overlooked or ignored.
The pages must have a significant amount of the same content for canonical to become effective.
If your web pages lack a large percentage of the same content, this is probably not your best option.
Another problem frequently encountered issue is when using the canonical tag with several related pages.
If, for example, you have a blog post and decide to break it down into different parts or sections, each will get their own unique URL.
When you use a canonical tag, essentially you are telling Google to show only one of these whenever someone searches for them.
In a 301 redirect, search engine bots permanently delete your old URL with the updated URL. In canonical, duplicate URLs are maintained but not indexed by the bots.
There is, however, no universal ‘better option’ redirection technique. One option is simply better in a certain scenario.
The bottom line, however, is duplicate content can potentially wreck your SEO ratings and both methods offer viable solutions for avoiding that.