Cardano (ADA) ADA

Cardano (ADA) is a proof-of-stake blockchain launched in September 2017 that supports smart contracts, native tokens and on-chain governance. It is known for an academic approach: its consensus protocol, Ouroboros, was published as peer-reviewed research before being deployed. ADA is the network’s native currency, used to pay fees, to delegate to stake pools and to vote. Here is how Cardano works, its history, its uses and the main criticisms.

What is Cardano?

Cardano was conceived in 2015 by Charles Hoskinson, an early Ethereum co-founder, and Jeremy Wood, who together founded the engineering company IOHK (now Input Output). The project was originally run by three entities: the Cardano Foundation in Switzerland (standards and promotion), IOHK (engineering) and Emurgo (commercial adoption). Since 2024, decisions have increasingly moved on-chain, with a member organisation, Intersect, coordinating development.

How Cardano works

Ouroboros proof of stake

Cardano uses proof of stake through the Ouroboros protocol. Time is divided into slots grouped into epochs, and stake pools are chosen to produce blocks in proportion to the ADA delegated to them. ADA holders can delegate their stake to a pool without sending their coins anywhere: the ADA stays in the holder’s wallet and can be moved at any time. Rewards are shared between pool operators and delegators. Our page on staking explains the general mechanism.

The eUTXO model and Plutus

Instead of Ethereum’s account model, Cardano uses an extended version of Bitcoin’s UTXO model (eUTXO). Smart contracts, live since September 2021, are written mainly with Plutus, a platform based on the Haskell language. The eUTXO model makes transaction outcomes more predictable, but it requires developers to think differently than on Ethereum.

Supply and monetary policy

The maximum supply of ADA is set at 45 billion. About 31 billion ADA were in circulation when the network launched; the rest sits in a reserve released gradually to fund staking rewards. Each epoch, a share of the reserve and the transaction fees are distributed, and part of it goes to a treasury that finances projects approved by the community. Because the reserve shrinks, new issuance decreases over time.

History: the main upgrades

• September 2017: mainnet launch (Byron era), with federated block production.
• 29 July 2020: Shelley hard fork, block production handed to community stake pools.
• 1 March 2021: Mary hard fork, native tokens.
• 12 September 2021: Alonzo hard fork, smart contracts.
• 22 September 2022: Vasil hard fork, performance and scripting improvements.
• 1 September 2024: Chang hard fork, first on-chain governance features.
• 29 January 2025: Plomin hard fork, full governance with delegated representatives (DReps) and treasury withdrawals voted on-chain.
• 18 July 2026: van Rossem hard fork (protocol version 11), which lowers smart contract execution costs. It was approved through on-chain governance by DReps, stake pool operators and the Constitutional Committee.

What is Cardano used for?

ADA is used to pay transaction fees, to earn staking rewards and to vote on governance proposals and treasury spending. The network hosts decentralised exchanges, lending protocols, stablecoins, NFTs and identity projects. Midnight, a privacy-focused partner chain developed in the Cardano ecosystem, launched its NIGHT token in December 2025.

Cardano vs Ethereum and Solana

• Approach: Cardano favours formal research and slow, planned upgrades; Ethereum and Solana iterate faster.
• Ledger model: eUTXO on Cardano, accounts on Ethereum and Solana.
• Staking: no lock-up and no slashing for delegators on Cardano.
• Ecosystem: Cardano’s DeFi activity remains smaller than that of Ethereum.

Risks and criticism

• Slow delivery: features such as smart contracts arrived years after launch, and critics say adoption has lagged behind the technical roadmap.
• Developer friction: Haskell and the eUTXO model narrow the pool of developers.
• Governance: on-chain governance is young, and voting power depends on how ADA is delegated.
• Regulation: in 2023 the US SEC named ADA in its lawsuit against Binance, a claim Input Output disputed; the SEC dropped that case in 2025.
• Market risk: like any crypto asset, ADA is volatile and can lose a large part of its value.

How to store ADA

ADA is listed on most large exchanges. To control your coins, use a Cardano wallet such as Daedalus (a full-node wallet) or Yoroi, or a hardware wallet that supports Cardano. You can delegate from these wallets while keeping your keys. Our guide to crypto wallets compares the options. Official resources and the full list of hard forks are on cardano.org.