Openzeppelin is a smart contract development framework which enables developers to write secure and reliable Ethereum contracts. OpenZeppelin has a collection of tested, well-tested code that developers can use as the foundation for their own smart contracts. OpenZeppelin provides multiple implementations of commonly used patterns in smart contract security, such as multi-sig wallets, address checksum verification, and efficient implementations of common cryptographic functions like SHA3.
The OpenZeppelin tag represents a topic that will be related to ZeppelinOS, smart contracts on Ethereum, and decentralized applications. These articles may include best practices for coding with Solidity, designing for security, developing on the mainnet or testnets, and tools for deploying applications.