Helo, im new at SEO and have this canonical for dummies quetstion. First of all, i do understand the principle of the tag, like making long adress easier to read for search engines. Take my webpage for instead, www . homepage.com/index, then i would be giving the other pages names such as /index/page1 /index/page2 /index/page3 and so on. I can't see the problem with long adresses, and since its all .html pages, its pretty static. But is it still recomended to use canonical then? I read this on a site about canonical: "Duplicate content is where two or more pages have the same content. The canonical tag is a piece of HTML code which can be placed on duplicate pages to indicate to a search engine where the original version of that page is" First of all, how can a page be duplucatet? When i upload index.com to the server, i only upload 1 unique orginal copy of that index.html. Is not that i upoaded 2 copies and then i have to point out which one of them is the orginal one. And beside, what does it mean that a page have the same content? does it mean like same H1 , same pictues on the page, same theme or same text. Or does it mean like exact same html code, just giving the file 2 difference name? who does that anyway? Thanks for all answers