For questions about the tangle, the directed acyclic graph which has the same function in IOTA as the blockchain has in other cryptocurrencies.
The Tangle is a directed acyclic graph (DAG) as a distributed ledger which stores all transaction data of the IOTA network.
It is a Blockchain without the blocks and the chain (so is it really a Blockchain?).
The Tangle as implemented in IOTA is the first public distributed ledger to achieve scalability, no fee transactions, as well as quantum-computing protection. Contrary to today’s Blockchains, consensus is no-longer decoupled but instead an intrinsic part of the system, leading to a completely decentralized and self-regulating peer-to-peer network.