IOTA's Tangle is an open, free and scalable distributed ledger designed to support frictionless data and value transfer.

IOTA is the first distributed ledger built for the "Internet of Everything," a network for exchanging value and data between people and machines.

The Internet of Things (IOT) is a term used to describe an interconnected network of smart devices. In theory, it could connect everything from locks, lights and appliances to cars, cities and energy networks in a vast network. In practice, however, this level of connectivity requires cheaper, faster, and more secure networks than many current systems can adequately support. For example, blockchain is very secure, but transaction costs and the difficulty of achieving the necessary predicted transactions per second (TPS) may require another approach. The directed acyclic graph (DAG) structure of IOTA is such a solution.

Designed for the Internet of Things, IOTA networks feature tamper-proof data, no charges for microtransactions, and low resource requirements.

Rather than linking together the transaction-filled blocks that build the blockchain, IOTA links together the transactions themselves. IOTA achieves this by requiring the counterparty to approve the two previous transactions and performing a small Proof of work (PoW) function. This "do-it-yourself" approach is arguably faster, simpler, and more straightforward than the standard blockchain-based PoW structure pioneered by Bitcoin (multiple third parties on the network perform more intensive PoW functions to help verify transactions). On the IOTA cryptocurrency platform, new transactions are linked to old ones in a similar way to how new blocks are linked to the end of a blockchain. However, their connective structures follow a different order. Blockchains are typically linked in a linear fashion -- transaction 1 connects to transaction 2, then transaction 2 connects to transaction 3, and so on. In contrast, a DAG is structured like a network, where a single transaction can connect multiple parent transactions as well as multiple sub-transactions.

For a node to issue a valid transaction, the node must solve a cryptographic puzzle similar to that found in the Bitcoin blockchain into the previous two transactions. This is done by finding a random number whose hash is linked with some data from the approved transaction and has a particular form. Suppose the node separately checks to see if any transactions are in conflict. There are no rewards for verifying transactions and no rewards for running full nodes. As transactions receive additional approvals, the system accepts them with a higher degree of confidence. As transactions receive additional approvals, their weight increases in proportion to the amount of work put into the issuing node. Each trade cited directly or indirectly accumulates additional weight. The time it takes for a transaction to be approved is inversely proportional to the volume of transactions sent over the network. Once a deal is approved, their weight will grow along with the flow of deals.

The Scalability of networks becomes stronger as the number of transactions increases. 2. Decentralisation: IOTA can achieve very high transaction flow and the more transactions are established, the faster the transaction confirmation rate will be. No transaction Fees: IOTA does not have a miner's design. Each person who establishes a transaction is also the person who validates the transaction. This means that everyone plays the same role in the consensus-building mechanism. Quantum Computing Protection

1. Address format, transaction format and Hash algorithm are all term-based (the Hash function based on the signature algorithm was changed to Keccak for security reasons several months ago, similar to SHA-3); 2. The structure of the transaction is in the form of Tangle. Each transaction quotes two previous transactions. 3. Snapshot technology, Snapshot technology can be used to reduce the occupation of hard disks, but it has not been officially enabled, at present, only in each major change of the code (equivalent to hard fork) to do Snapshot (that is, in the source code solidified in all addresses of the entire network currency number); 4. The transaction fee is 0, which is the biggest advantage of IOTA. Because IOTA does not depend on miners, nor does it exist and does not need incentives, the transaction fee can be 0. 5, the one-time signature technology, due to the one-time signature technology every signature reveal that part of the private key, as the number of signatures growth, the security of private key into index decreased, so spend only once each address (note that the seeds of the private key is not IOTA purse, every address generated by a seed have independent private key, A seed can generate an unlimited number of private keys); 6. Using a technology similar to Hashcash, each transaction requires a certain amount of PoW to be accepted by the network.

IOTA completed token sales and distributed 999.9 million IOTas in 2015, raising a total of 1,337 Bitcoins, or $434,000 at the time. The supply was later revised to 2.78 billion IOTA. Five percent of the funds from IOTA's token offering were later donated to the IOTA Foundation.

IOTA now faces competition from other DAG distributed ledgers with different design features that some like, including Nano and Hedera Hashgraph (HBAR).

IOTA and other distributed ledger DaGs are promising but not yet technologically superior to blockchains. While many focus on iot use cases, IOTA and other DAGs can also be used for data storage, communications, microtransactions, smart contracts, and more. IOTA is free, fast, and has good scalability potential, but some have questioned the viability of the network given its past security flaws; Others say it must accept devolution before it can be taken seriously.

On the other hand, proponents say IOTA's roadmap is one of the most transparent in the crypto space. IOTA has also made changes for the better and developed stronger security protocols and testing. Others added that IOTA is a very ambitious project that aims to provide a permissive, autonomous, decentralized and free ledger network to facilitate the adoption of the Internet of Things, which will affect a wide range of industries.

1. IOTA has not been extensively combat-tested. 2. Centralized risk. 3. Security loopholes.

IOTA and DAG's competitors will play a key role in facilitating the iot ecosystem that is taking off. The US government has also expressed particular interest in using the Internet of things. It reserves L-band radio frequencies for 5G and the Internet of Things. These frequencies are another infrastructure component that, along with the secure network, will enable the iot ecosystem to flourish in the years to come.