Smart Contracts on a Blockchain ✅
Definition
A smart contract is a self-executing program stored on a blockchain that automatically enforces rules and conditions without requiring a third party. Once deployed, it runs exactly as programmed, and cannot be altered or tampered with.
Why Use Blockchain for Smart Contracts?
Deploying smart contracts on a blockchain provides:
- ✅ Security – Immutable and tamper-proof code execution
- ✅ Decentralization – No single point of control
- ✅ Transparency – All parties can verify contract behavior
- ✅ Automation – Contracts execute automatically once conditions are met
Platforms Supporting Smart Contracts
- Ethereum: Most popular platform using Solidity language.
- Bitcoin: Limited scripting (e.g.,
nLocktime,CLTV) enables basic contracts. - Other Platforms:
- Hyperledger Fabric – Uses Java, Golang, JavaScript
- EOSIO – Uses C++
- Lisk – Uses JavaScript
- Stellar, Tezos, Neo, Monax, Counterparty also support smart contracts
Example: Bitcoin vs Ethereum Smart Contracts
| Feature | Bitcoin | Ethereum |
|---|---|---|
| Smart Contract Support | Very limited (basic scripts) | Full-fledged smart contract support |
| Language | Script (non-Turing complete) | Solidity (Turing complete) |
| Example Use | Time-locked transactions | DApps like DeFi, NFTs, etc. |
Important Requirements
- Determinism: Code must produce the same output on every node
- Security: Vulnerabilities (e.g., DAO attack) show how important secure development is
- Bug-Free Code: Smart contracts are immutable once deployed — errors can’t be patched easily
Languages Used
- Solidity: Ethereum
- Vyper: Ethereum alternative (security-focused)
- Java, Go, JavaScript: Hyperledger
- C++: EOSIO
- JavaScript: Lisk