Directed Acyclic Graph (DAG)

What is DAG?

DAG known as Directed Acyclic Graph is a data structure that uses topological ordering.DAG is an implementation of directed graphical structure.DAG is mostly used for solving problems such as data processing, finding the best route for navigation, scheduling, and data compression.
DAG graph only involves transactions thus avoiding the need for the mining process. Thus DAG is known as Blockless data ledger that only contains transactions and eliminates the need of miners for mining a new block.
Thus DAG reduces the transaction time and improves scalability that seems to be a bottleneck in the blockchain.

Concepts of DAG

Elimination of Minning

Bitcoin blockchain involves the process of mining and miners to validate a transaction. DAG network eliminates the mining process and the transactions go directly into the validations themselves.
Thus DAG supports for automated validations and no miners, results in safer, secure faster and instant transactions.

Shorten the Width of Network

In the blockchain, while validating a transaction it links to the previous transaction which might result in widening the network. In DAG, after validation, every transaction are linked to a new and also an existing transaction on the network.
Therefore, DAG prefers an existing later transaction to link to a new transaction. The goal of DAG is to keep the network width under a certain range that can support quick transaction and its validation.

Swift Transactions

As DAG has blockless nature, the transactions run directly into the networks which make for quicker transactions. The whole process of transactions on the DAG network is much faster than those of blockchains that are based on PoW and PoS.
Best Suits for Small Payments
DAG technology was introduced with the idea of making smooth and faster transactions with the lowest fees. This creates a way through which users can send micro-payments with lower fees and not heavy as Bitcoin or Ethereum.

Double-Spending Issues

Bitcoin Blockchain uses unspent Transaction Output Model, which makes users to have only one transaction.
In DAG, the validation of every transaction depends on the number of transactions supporting it. The rate of transactions entering the network is lower, which makes transactions safer and faster.

Platforms / Technologies Based on DAG

IOTA

IOTA is the first DAG-based cryptocurrency project, that aims to eliminate the concept of a miner’s fees. IOTA initially designed to serve as a backbone for the Internet of Things( IoT), but later its features are utilized for other endless use cases.

NANO

NANO platform uses a weird architecture, i.e. block-lattice which is similar to that of the lightning network.
Instead of keeping the history of the entire blockchain and its branches called side-chains, NANO a new network topology where every account has its own blockchain called as account-chain. This enables for quicker transactions.
Soure : Bitdeal