Both! It uses distributed computing to mine and transfer data, certificates, assets, etc. It is decentralized since no one person can control it (like Bitcoin). If you are referring to the marketplace, it is directly on the Blockchain, anyone can build their own centralized or decentralized marketplace on top of the Syscoin code; an individual can sell their goods or services directly on the Blockchain, but a business can also use the Blockchain for the sale of goods or services. Developers will be able to easily include the Blockchain's code directly into their site or ecommerce platform. This in essence is why we chose the motto "Business on the Blockchain"