Smart contracts are self-executing contracts with the terms of the agreement directly written into code. They run on a blockchain, a decentralized and distributed ledger technology that ensures transparency, security, and immutability. The concept of smart contracts was introduced by Nick Szabo in the 1990s, but it gained practical implementation through blockchain technology, particularly with platforms like Ethereum.

Here are key characteristics and features of smart contracts:

Self-Executing: Smart contracts automatically execute and enforce the terms of an agreement when predefined conditions are met. They eliminate the need for intermediaries or third parties to oversee and enforce contracts.
Decentralization: Smart contracts run on a decentralized blockchain network. This means that the code and its execution are distributed across multiple nodes in the network, reducing the risk of a single point of failure and increasing security.
Transparency: The code of a smart contract is typically open source and visible on the blockchain. This transparency ensures that all parties involved can verify the terms and conditions of the contract, promoting trust.
Immutable: Once deployed on the blockchain, smart contracts are typically immutable, meaning their code cannot be altered or tampered with. This ensures that the terms of the contract remain unchanged once agreed upon.
Trustless Execution: Smart contracts execute automatically without the need for trust between parties. The code determines the outcomes, and participants can rely on the blockchain's decentralized and secure nature to ensure fairness.
Conditional Logic: Smart contracts can include complex conditional statements and logic. They can execute different actions based on specific conditions being met or not met, allowing for a wide range of applications beyond simple transactions.
Cost and Time Efficiency: By automating the execution and enforcement of contracts, smart contracts can reduce the need for intermediaries, paperwork, and manual processes. This can result in cost savings and faster transaction times.
Use Cases: Smart contracts find applications in various fields, including finance (e.g., decentralized finance or DeFi), supply chain management, voting systems, insurance, and more. They enable the creation of decentralized applications (DApps) that operate on blockchain platforms.

Ethereum is the most well-known blockchain platform for developing and deploying smart contracts, but other platforms, such as BNB Chain, Polkadot, and Solana, also support smart contract functionality. Developers use programming languages like Solidity (for Ethereum) to code smart contracts, and users interact with them through transactions on the blockchain.