Proof of Work guarantees the security of the system by resource-intensive transmission and validation of a multiplicity of data between the different users in the system. The proof of work is defined by the extensive calculation of complex computation tasks — difficult to perform but simple to check. This mining leads to a trustworthy, decentralized consensus and at the same time, by creating digital currencies (mining), guarantees the reward for these miners. The system can only be manipulated if a user owns more than 50% of the computing power and their system permanently works faster than the systems of the other users. It is impossible to fulfil these two conditions together. As well as the PoW process, there are further methods of ensuring consensus (→Proof of Stake, →Proof of Authority, →Second Layer).