IOTA is promising. IOTA will enable nano payments. IoT devices can use IOTA to interact with each other and take actions if necessary. The devices will be able to transfer funds, keep records and send messages to each other without need of any centralised system.
In IOTA, the device initiating the transaction will do a little PoW of broadcast the transaction to the network. It gets linked to another two transactions. As no miners are involved, the transactions are free and fast.
But IOTA is not a blockchain. It uses another consensus protocol named Tangle. If you are looking for a blockchain project, IOTA is not the one for you.
Blockchain in simple terms is chain of blocks. Each blocks consists of several transactions. These transactions are identified by their block height. All the blocks are linked to each other. It makes it easy to find and identify particular transactions. It increases security as to change a particular transaction, you will have change informations in preceding blocks too.
Tangle is a new concept by IOTA developers. They wanted a solution which has no mining, no transaction fees and are fast. In Tangle, transactions are linked to each other like a big web tangle. Their is no concept of blocks. Each transaction will be verified by a little PoW by the originating device. It will link the transaction further to two more random transactions.
In Tangle, you do not need to wait for blocks to be mined. The transactions are verified parallelly. This helps in fast and more number of transactions at a time.
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People are concerned about rising electricity costs in Bitcoins. Or centralisations of miners. IOTA is an answer to them. It is still in very early stages. It has not faced the problems that Bitcoin faced. When implemented properly, you can see IOTA being used in your cars, homes, phones and every other electronic device.