: Two Questions about Canonical Tags 1) Queries in the URL For example, I was reading a blog post that said suppose you have the following links: example.com/quality-wrenches.htm (the main page)

1) Queries in the URL

For example, I was reading a blog post that said suppose you have the following links:

example.com/quality-wrenches.htm (the main page)

example.com/quality-wrenches.htm?ref=crazy-blog-lady

example.com/quality-wrenches.htm?sort=price

Then the blog post suggested that in the header of the above pages, you could place a canonical tag that points to the main page.

My question is, how can you technically place a header in pages with queries like ?ref and ?sort ? Can you actually go into your webhost's directory and find "/quality-wrenches.htm?sort=price" and edit its HTML?

Or is what the blog post suggesting is that you simply place a self-referencing canonical tag in example.com/quality-wrenches.htm (the main page), and then example.com/quality-wrenches.htm?sort=price would automatically have that canonical tag?

2) Self-referencing canonical tags

I've read that it's good to do this just in case other websites copy your content, but what if other websites use self-referencing canonical tags when using your content?

How will google know which site to index?