Although canonical is not a brand new concept I keep seeing loads of bad implementations. So I thought it was worth creating some slides to recap the best practices.

1. Canonical tag implementation

2. What is the canonical tag?
Canonical tag has been rolled out to tackle
duplicate content issues, but it may be slightly
confusing because:
• It can be used in many “creative” ways
• It has the potential to break your site

3. The good
It’s very easy to implement and it looks to work
quite well for URL like:
• Faceted / sorted searches
• Tracking parameters / Session ID
• Duplicate content across categories navigation
• Useful for circumstance where 301 is not easy to
be implemented (e.g. affiliate links)

4. The bad
• It has been allegedly said to consolidate the link
juice / popularity
• It’s not a replacement for fundamental URL
structure
• It may fall down with contradictory
implementations
• It’s still an hint and not a directive, hence it’s up
to Search Engine stick on it

5. A (bad) implementation example
The code suggests the canonical URL of the Drupal node setup as the home
page as the URL to be indexed, but…

6. The suggested URL do a redirects
Thus making the previous canonical useless.

7. To canonicalize or to not canonicalize?
Google stated “there is not a problem to use the
canonical tag on every pages of your site”.
On the other side, Bing says “using it everywhere
(as a placeholder) is essentially telling us the page
to be a copy of itself”.
What a dilemma!

8. Best practices to comply with all SEs
Canonical tag implementation should not be seen in
isolation as multiple factors contribute to site’s visibility.
As general principles, use a canonical tag bearing in
mind that:
- Redundant code make pages loading slower
- Canonical is not an excuse to ignore URL best practice
- Use the 301 redirect every time it is possible
- Consistently links pages
- Canonical tag not to point to Error pages