Cardano is a Proof of Stake blockchain that runs smart contracts and has its own native asset, ADA. It was founded by Charles Hoskinson, one of the co-founders of Ethereum, and its mainnet launched in September 2017. The project is known for basing its protocol design on published academic research. The official Cardano website describes the network and its goals.
Who Builds Cardano
Three organizations were set up to support the network. Input Output Global (IOG, formerly IOHK) is the engineering and research company that designed much of the protocol. The Cardano Foundation is a Swiss non-profit that promotes adoption and oversees the brand. Emurgo is the commercial arm. Since 2024, ADA holders have also had a direct role through on-chain governance.
Ouroboros Consensus
Cardano's consensus protocol is called Ouroboros. The original paper was peer reviewed and presented at the Crypto 2017 conference. Its authors describe it as the first Proof of Stake protocol with a formal proof of security.
Time on Cardano is divided into epochs of five days, and each epoch is divided into one-second slots. For each slot, the protocol selects a stake pool to produce a block, with the chance of selection proportional to the stake delegated to that pool. On average a block is produced about every 20 seconds.
Finality is probabilistic, as it is in Bitcoin. A transaction becomes harder to reverse with each block built on top of it. A transaction can appear in a block within a minute, but that is not the same as instant, absolute finality.
Staking and Delegation
ADA holders can delegate their stake to a pool from their own wallet. Cardano's design here differs from many other networks in three ways.
- No lock-up: delegated ADA stays in your wallet and can be spent or moved at any time.
- No slashing: a pool that performs badly earns fewer rewards, but delegators' ADA is not confiscated.
- Pool saturation: rewards taper off once a pool grows past a set size, which pushes stake toward many pools instead of a few large ones.
Rewards are calculated per epoch and begin after a delay of a few epochs. Pool operators charge a fixed fee and a percentage margin, both visible in the wallet.
The Extended UTXO Model
Ethereum tracks balances in accounts. Cardano uses an extended version of Bitcoin's UTXO model, where a transaction consumes existing outputs and creates new ones. The outcome and the fee of a transaction can be worked out before it is submitted, so a valid transaction does not fail halfway and still charge a fee the way it can on Ethereum.
The model also makes some designs harder. Many users interacting with the same contract state at once requires careful engineering, which early Cardano DEXs had to solve.
Tokens other than ADA are native assets. They are handled by the ledger itself and do not need a smart contract to exist or be transferred.
Smart Contracts
Smart contracts arrived with the Alonzo upgrade in September 2021. Contracts run on a platform called Plutus. Developers originally wrote them in a Haskell-based language. Aiken, a newer language built for Cardano, compiles to the same on-chain code and has become a popular choice. The Cardano documentation covers the developer tools.
The ecosystem includes decentralized exchanges such as Minswap and SundaeSwap, lending protocols, stablecoins and NFT marketplaces. It is much smaller than Ethereum's by value locked and by developer count.
Development Eras
Cardano's roadmap is organized into named eras.
- Byron (2017): the launch era, with ADA transfers on a federated network.
- Shelley (2020): staking and delegation, with block production handed to community stake pools.
- Goguen (2021): native tokens and smart contracts.
- Basho: scaling work, including Hydra, a Layer 2 protocol for fast off-chain transactions.
- Voltaire: governance and treasury control by ADA holders.
Governance
The Chang hard fork in September 2024 began the move to on-chain governance. ADA holders can delegate their voting power to delegated representatives, known as DReps, or register as one. Governance actions are voted on by three groups: DReps, stake pool operators and a constitutional committee. A second upgrade in early 2025 completed the system, and a constitution was ratified on-chain.
Project Catalyst is a separate, older program in which ADA holders vote on grants for community projects.
Cardano vs Ethereum
Both are Proof of Stake smart contract platforms. Ethereum launched contracts in 2015 and has far more applications, liquidity and developers. Cardano shipped features later and places more weight on formal methods and peer review. Supporters see that as care. Critics see it as slowness. The two also differ in accounting model, contract languages and staking rules, so applications cannot simply be copied from one to the other.
Risks to Understand
- Adoption: DeFi activity on Cardano is small compared with Ethereum, Solana and several Layer 2 networks.
- Competition: many platforms compete for the same developers and users.
- Development pace: some long-planned scaling features have taken years to arrive.
- Smart contract risk: applications can have bugs regardless of how carefully the base layer was designed.
- Volatility: ADA has fallen very sharply from its highs in past bear markets.
A common mistake is assuming staked ADA is locked. It is not, and nobody needs your seed phrase for you to delegate. Any site asking for it is a scam.
Nothing in this article is financial advice.
Key Cardano Facts
- Mainnet launch: September 2017
- Founder: Charles Hoskinson
- Consensus: Ouroboros Proof of Stake
- Maximum supply: 45 billion ADA
- Epoch length: five days
- Smart contracts: live since September 2021
- On-chain governance: began with the Chang hard fork, September 2024
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