Blockchain is a technology that is in use increasingly. Although owing its common use to the cryptocurrencies there is more to the blockchain technology than just the monetary use. One of these uses is by smaller groups of participants under the control of a central authority, for instance at a company. Such private blockchains use permissioned blockchain consensus algorithms as the participants need the permission of the authority to be able to join the system. This paper will give an overview of the blockchain technology, investigate permissioned and permissionless blockchain, and focus on permissioned blockchains to analyze it in terms of, e.g. trust models between the nodes, incentives, number of nodes & parties involved, and scalability regarding the number of transactions.