IOTA is a cryptocurrency powering an open source protocol aimed at providing the backbone of the Internet of Things (IoT). The ledger, called the Tangle, was launched October 21st 2015 by founders David Sønstebø, Dominik Schiener, Serguei Popov. Unlike other cryptocurrencies, IOTA is not powered by a blockchain but rather a Directed Acyclic Graph (DAG). This makes the ledger notably different that other cryptocurrencies using a blockchain ledger. Firstly, there are no transaction fees, with users paying for fees by confirming 2 past transactions for every 1 transaction submitted. This results in the network speed increasing the more users use the network. Secondly, since transaction fees are replaced with the user confirming 2 past transactions, there are no miners and thus no block rewards. Transactions sent to the tangle do not require any IOTA to be sent, resulting in transactions only containing messages possible.
The code repository for Ethereum can be found at: https://github.com/iotaledger
Type: Directed Acyclic Graph
Start: October 21st 2015
Hash Function: Troika