Hi, I'm planning to start a quite serious online business and I need you thoughts on domain and seo related subjects. Background: It will be a some kind of a marketplace. I will help the buyers to find suitable seller, help sellers drive buyers to their offers etc. So there are two kind of my clients: sellers and buyers. And there are a few services: sellers search for the buyers, membership forum for the sellers to exchange knowledge, sellers mini sites (I will host them), some general knowledgebase. I got also one nice domain for this business (let's call it maindomain.com ). Question: What is better from the users (usability), business brand and seo (site authority building, promoting) perspective: - to create a subdomain for each type of service (eg. findseller.maindomain.com, forum.maindomain.com, seller1.maindomain.com, seller2.maindomain.com...) - create separate domains for each service (eg. findseller4you.com , sellersforum.com, seller1.hostsellers.com. seller2.hostsellers.com) - mixing it, or someting completely different? Do you know a business with a similar model and how do their domains look like? Looking for your serious advice! Take care, D.