The main innovation behind IOTA is the Tangle, a revolutionary new blockless distributed ledger which is scalable, lightweight and for the first time ever makes it possible to transfer value without any fees. Contrary to today’s Blockchains, consensus is no-longer decoupled but instead an intrinsic part of the system, leading to decentralized and self-regulating peer-to-peer network.
3 years already in production. This could be a pivot to feeless transactions, and I could see this at some point compete directly with existing blockchain protocols. Nonetheless, its a very interesting project and I implore more humans to look at it before all the machines pick it up ;)
Here is a beautiful visualization of the tangle ledger in real-time. https://tangle.blox.pm/
Purple dots represent new and unvalidated transactions (called "tips").
Every time you send a new transaction on the tangle, you're doing your PoW, which result on a validation two "random" transactions in the tangle. That's why every purple dot is linked to two white dots.