DAG (directed acyclic graph) - is a structure which is used in Cellframe zero-chain. DAG consists of [[Event|events]], each event can contain only one data type ([[Data element (Datum)|datum]]). Events are collected in sets, form connected graphs, and are called a [[Round]]. The round on forming stage is placed in the [[Global Database (GDB)]], not in the chains, then is carried from GDB to the chains after the minimum time has passed, if it becomes connected. The DAG, instead of a clear sequence of blocks, writes information non-linearly, without a sequential chain of blocks. The reliability of the algorithm is mathematically described as Asynchronous Byzantine Error Tolerance (ABFT). Algorithms are very difficult to hack, and more than two-thirds of the participants need to agree to make a decision at the network level. Due to DAG, the hashgraph has all the advantages of the blockchain, while demonstrating a higher transaction performance. In general, the hashgraph works as follows: network participants (nodes) exchange data over the network, information about the transaction is sent to two random nodes, transmitting them, in turn, to two other nodes - and so on exponentially, until the volume of informed nodes becomes sufficient for verification of the transaction; nodes exchange with each other only transaction data, and not all information about the network; transactions are recorded in chronological order - you can track their history. In the hashgraph, each node knows the entire transaction history, therefore, to achieve consensus, “virtual voting” is used - there is no need to coordinate all the nodes with each other: each of them already knows how the other node will “vote”. Other advantages of DAG are: scalability and performance - up to 500 thousand transactions per second (potentially - up to a million); an increase in the number of network participants increases the bandwidth; low resource consumption and high resistance to DDos attacks and botnets; no need for mining and [[Proof of Work (PoW)]]; commissions close to zero.