Currently the IOTA network uses a central Coordinator node for security of the network.It can be thought of as walking towards the heaviest branch.As a result bigger branches get bigger, and smaller branches shrink and eventually disappear. The walk is biased towards transactions with more cumulative weight, or more transactions approving them. The walk is performed twice, and so two tips are chosen. Tip selection is done by performing a random walk from the genesis towards the tips.Java client for IOTA is available at.This does not mean however that its application is limited only to IOT. This makes it very suitable for machine to machine traansactions at scale such as those involved in IOT.Because there are no miners in the Tangle, and the responsibility for validation is an intrinsic part of issuing a transaction, there are no transaction fees.In Tangle, because transaction issuance is tightly coupled with network validation, transaction confirmation can be achieved in a fraction of the time it takes for Blockchain.The more activity in the Tangle, the faster transactions can be confirmed.

This structure also enables high scalability of transactions.This makes sure there are no double-spends or new illegitimate tokens created. In particular, it means all accounts have positive balances. Approving a transaction implies that its history was verified and found to be valid.In order to make a transaction in the Tangle, two previous transactions must be validated with the reward for doing so being the validation of your own transaction by some subsequent transaction.a participant in IOTA simply needs to perform a small amount of computational work that verifies two previous transactions in Tangle.This DAG structure allows transactions to be issued simultaneously, asynchronously, and continuously, as opposed to the discrete time intervals and linear expansion of a Blockchain.Directed because all the reference pointers point in the same direction, acyclic because there are no loops, and a graph because the reference pointers and transactions form a graph of edges and vertices. In Tangle each transaction (not a block of transactions) references two previous transactions, forming a Directed Acyclic Graph, or DAG.When a new transaction is introduced, it is added as a new vertex in the DAG. The vertices represent transactions, and edges represent approvals.These transactions are distributed and stored across a decentralised network of participants. The IOTA Tangle is a stream of interlinked and individual transactions.IOTA on the other hand stores streams of trasactions in a directed acyclic graph.

Most Blockchain platforms such as ethereum,bitcoin and hyperledger store transactions in a sequence of blocks where each block maintains a connection to the previous block thereby creating a chain of blocks.

IOTA's distributed ledger is called Tangle.

Iota tangle full nodes