I would like to know if canonical is needed in the next example.
The content is equal to www.example.com. Should I define <link href="http://www.example" rel="canonical" /> ? is it really needed to avoid duplicate content ?
In general, search engines are much better at detecting multiple routes to the same content when you use query URLs, so you are less likely to suffer duplicate content problems just by having a query parameter stuck on the end. That said, I wouldn't like to categorically say that you will definitely be OK, and it doesn't hurt to use a canonical link, so I tend to do it as a matter of course.
Its always better to stay on the safe side. So its better if you use the canonical tag.
Good thing about canonical tag is that you can post same content on multiple sites, designate which url you prefer to get all the credit, then place a canonical tag with that url on each of those pages.
this is canonical tag to use. need to redirect the Duplicate URL to original URL to Remove the Content duplicated or cache restriction from Robots.txt
Google dont like this .Google has now launched its new update called "diversity update".It is absolutely against this method.You cannot put the same url in the different sites.
Before we stray too far from the original question, might I suggest reading Google's advice about the use of the canonical tag?
With Canonical, the main problem, other than Duplicate Content, is that you compete with your own website, viz., example.com and example.com?hi. To avoid this, we should not be having any canonical pages.
What do you mean by that? The whole point of using the canonical tag is that it means search engines don't see your site as having duplicate content or multiple pages competing for the same text.
How are TAGS considered now with the latest Google Update? Do they count it as duplicate again? I know for a while if you had tags on say a wordpress site (a lot of them) that Google would over-look it. Is that still so???