Multiple domains vs. subdomains vs. folders

This extremely useful article shows the advantages and disadvantages of various possibilities to structure a website. While going for a different domain (e.g. instead of to easily geo target for a foreign market might be a great advantage, no authority or trust is being passed by the domain that already exists, which obviously is a huge disadvantage. Like always, first of all you should focus on your goals – what do you want to achieve now, where do you want to be in five years? A clear and constant website architecture is a make or break for SEO, so I really recommend you to read the whole article, which also has a very clear short summary at the end