Support same URL in different forms

Question

I have seen many websites supporting multiple forms of the same URL. For example consider

• www.example.com/question1/ OR
• www.example.com/Question1/ OR
• www.example.com/QUESTION1/ etc.

all lead to one page with say

<link rel="canonical" href="http://www.example.com/question1/" >

or a 301 redirect to www.example.com/question1/.

Does this affect the page rank anyhow or its just for seemless user experience or there is some other reason behind this?

Infact even stackoverflow/stackexchange does this. No matter what the text after the id of the question in URL they redirect you to the correct question!

Answer 1

It is for "seemless user experience". The canonical URL should stay the same for each document, regardless how it was called.

Answer 2

Having different forms of a url and choosing one to be "correct" is called "URL canonicalization". URL canonicalization is important for SEO

• It prevents duplicate content where search engines see multiple pages that have the same content
• It consolidates PageRank (link juice) to the canonical URL
• It prevents search bots from crawling many duplicate pages which can overload servers and confuse the bots.

Until recently, only redirects were available for implementing URL canonicalization. Now that Google has introduced rel canonical, there are two options.

301 Redirects

• Users all the the same single URL for a piece of content
• If a user comes to a non-canonical URL, they are redirected to the correct one
• Users that choose to link to the site will almost always link to the canonical URL
• Search engines see a single URL for a piece of content
• If a search bot comes to a non-canonical URL, they are redirected to the correct one
• Tracking parameters on URLs get stripped of and may stop working -- cookies must be used instead

Rel Canonical

• Users may see different URLs for a singe piece of content
• If a user comes to a non-canonical URL, they are shown the content
• Users that choose to link to the site may choose to link to a non-canonical URL
• Search engines index a single URL for a piece of content
• If a search bot comes to a non-canonical URL, they are referred to the correct one
• Tracking parameters on URLs remain on and continue working
• Can introduce very subtle bugs since any problem with a canonical tag is not easily visible to users.

Answer 3

301 are generally better but not always possible. If you can do a 301, that is what I would recommend. There may be some exceptional situations when the reverse is true but I cannot think of any right now. Regardless:

• For SEO, a 301 is a definite answer. The 301 indicates the URL uses has been replaced by the target one. There is no leeway for crawlers to interpret this. Canonical tags are good too except that they are suggestions and a search engine can choose to ignore them.

• For visitors, a 301 sends them to the right place. This lets them share the correct URLs with their friends, social-media, etc which is probably better for your site anyway.

So, if you can, because it is in fact the same page, prefer 301 redirects. If you have pages with the virtually the same content then you have to resort to canonicals. An example would be pages with the same content in different order.