IOTA is a decentralized, micro-transaction token that is geared towards the Internet of Things (IoT). The crypto-token runs off of Tangle, which has similarities to a blockchain but is much more versatile.
The Tangle Ledger
Tangle is a cryptocurrency that was developed for the Internet of Things in 2015. The aim of the project was to enable machine-to-machine payment transactions and ensure accurate and consistent data was being maintained. The idea was conceived when the creators realized that most internet-connected devices need a secure way to transfer data and transactions in order for the whole IoT to work smoothly. You can read more about Tangle here (PDF).