Is Alexa mainly used for English speaking sites? I haven't heard of it used for other languages but does it function for reading traffic from other languages as well or is there another site for this?
I use it for all sites (not only English speaking). But sure, English speaking people more often install alexa toolbar.
I also remember to have seen Alexa ranking for many sites other than English sites. It is a universal ranking system.
http://www.alexa.com/topsites
In just the top 20 you can see all sorts of sites not in English. You got QQ.com, Yahoo!カテゴリ (Whatever that is), Google India, etc.
No,it works well for English site as English speaking country visitors often have alexa toolbar on their browser
Actually not English only