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The Tangle

Mon, 01 Jan 0001 00:00:00 +0000

The Tangle was IOTA’s original ledger: a directed acyclic graph (DAG) of transactions rather than a chain of blocks. It defined the network from launch until the IOTA Rebased upgrade in May 2025 retired it. Understanding it still matters, because most third-party material describes IOTA as if the Tangle were the live system.

What the Tangle Is#

In a blockchain, miners or validators batch transactions into blocks and link the blocks in a line. The Tangle had no blocks and no dedicated block producers. Each new transaction directly approved two previous transactions by referencing them, forming a growing mesh:

IOTA Rebased

Mon, 01 Jan 0001 00:00:00 +0000

IOTA Rebased is the protocol overhaul that went live on mainnet on 5 May 2025. It retired the Tangle as IOTA’s ledger and replaced it with a Move-based object ledger, delegated proof-of-stake consensus, and real transaction fees. The architecture is derived from the same Mysten Labs research lineage as Sui — IOTA effectively rebased its mainnet onto that stack, hence the name.

What Changed#

	Pre-Rebased (Tangle)	Rebased (May 2025+)
Ledger	DAG of transactions	Object ledger on the Move VM
Consensus	Tip approval + Coordinator milestones	Mysticeti dPoS, no Coordinator
Validators	Foundation Coordinator	Up to ~150 permissionless, staked
Fees	None	~0.005 IOTA per tx, burned
Finality	Probabilistic (cumulative weight)	Deterministic, sub-second
L1 smart contracts	None	Native Move

Object Model and the Move VM#

Instead of accounts-with-balances (Ethereum) or unspent outputs (Bitcoin, legacy IOTA), state is a set of typed objects owned by addresses. Smart contracts are Move modules; assets are Move resources — values the type system forbids from being copied or implicitly dropped, which structurally prevents whole classes of double-spend and accounting bugs.

IOTA EVM

Mon, 01 Jan 0001 00:00:00 +0000

IOTA EVM is IOTA’s fully Ethereum-compatible smart-contract chain. It is the practical entry point for DeFi on IOTA: existing Solidity contracts, ERC-20 tooling, MetaMask, Hardhat, and Foundry all work unmodified, with configuration changes only. It launched on mainnet in 2024 and continues to run as a Layer 2 alongside the Move Layer 1 introduced by the Rebased upgrade.

Architecture#

IOTA EVM is one chain produced by IOTA Smart Contracts (ISC), the framework that runs sandboxed contract chains and anchors their state to IOTA Layer 1. From a developer’s point of view it is an ordinary EVM chain; the ISC layer underneath handles settlement to L1 and asset movement. The native IOTA token is the gas currency, and a bridge moves value between L1 native assets and L2 EVM balances.