IOTA mission is to power the future of the Internet of Things (IoT) with feeless micro transactions. IOTA doesn’t use a blockchain but instead a DAG (directed acyclic graph) also referred to as a “tangle”.
IOTA also introduces a new way of reaching consensus. The system has no miners and instead network participants need to perform validation in order to transact. This happens in parallel, so the architecture is intended to make the system very scalable: The more nodes the network has the more secure and fast it becomes.
Please see project website.