Google and querystring parameter capitalization?

Question

I looked all over the web, but I could not find an answer to this. We all know that Google treats different capitalization of Urls as potentially duplicate content.

My question is, what about querystring parameters? For example, will Google treat this as duplicate content?

http://www.example.com/forum?thread=first

and

http://www.example.com/forum?Thread=first

Here, the url has the same capitalization. However, the querystring parameter "Thread" and "thread" have different capitalization for the letter "T".

How does Google treat querystring parameter capitalization? Does it ignore querystring parameter capitalization or will different querystring parameter capitalization lead to duplicate content penalties from Google?

Answer 1

This isn't really about Google, it's about the specification for URLs - lower and uppercase are different URLs. This applies to query string parameters as well.

If Google knows of 2 different URL variants, it treats them initially as 2 separate URLs. However, if it turns out they have the same content, Google is generally smart enough to count them as the same page.

The best solution is to add the canonical meta tag with the "perfect" version of the URL (e.g. all lowercase). This will make it perfectly clear to all search engines what URL they should use.