Composability has its roots in computer science, particularly in software engineering and object-oriented programming. Its modular design principles enable code reusability, deployment, and portability by breaking down a system into smaller, independent components. In addition to modular designs, protocol standardization are also part of composability, which allows developers to build new applications by leveraging existing functionalities without having to reinvent the wheel. In the blockchain ecosystem, such standards may apply to the architecture design sets, or the protocols of blockchain native assets or smart contracts. >[!tip] While composability may generally refer to components within systems, *full composability* refers to software components which can seamlessly be ported or implemented across different systems. Fully composable smart contracts or assets can easily be used or executed on a non-native blockchain or sidechain without requiring significant modifications. >[!examples] >Blockchains implementing composability include: >1. Ethereum: The most prominent example is Ethereum itself, where various DeFi protocols like lending platforms (Compound), decentralized exchanges (Uniswap), and stablecoins (DAI) are built using composable smart contracts. These protocols interact with each other through standardized interfaces such as ERC-20 tokens. >2. Polkadot: Polkadot is a multi-chain network that facilitates interoperability between different blockchains called parachains. Parachains can communicate with each other using cross-chain messaging passing (XCMP) protocol, enabling composability across multiple chains within the Polkadot ecosystem. >3. Cosmos: Similar to Polkadot, Cosmos is another project focused on enabling interchain communication among independent blockchains called zones via its Inter-Blockchain Communication Protocol (IBC). Composability is achieved by allowing zones to interact with each other and share data or assets. >4. Binance Smart Chain (BSC): BSC is a blockchain platform compatible with the Ethereum Virtual Machine (EVM), which means it supports Ethereum-based smart contracts. This compatibility allows developers to port their existing Ethereum DApps to BSC, maintaining composability across both networks.