Because of its design, IOTA is vulnerable to a 34% attack. This means that an attacker who controls 34% or more of the computing power on the IOTA network will be able to perform transactions at will. To protect IOTA from a hostile takeover, the coordinator was introduced. The coordinator is not part of the IOTA protocol, but confirms as a centrally controlled entity, incoming transactions in a certain time interval. This should be imagined as a kind of support wheel that prevents the IOTA network from being successfully attacked during its infancy. The disadvantage of the coordinator, on the other hand, is that it prevents the network from achieving the performance in terms of transactions per second that would at least theoretically be possible. For this reason alone, the goal must be to turn the coordinator off in the long run. The way to achieve this is explained in detail in a 5-part blog: The Path to Coordicide.

Once the coordinator is turned off, IOTA will be the only fully distributed ledger technology, with the limit of throughput determined solely by the underlying physical characteristics of the medium through which the transactions are transmitted. More information about coordicide at coordicide.iota.org