A public blockchain is an open, decentralized network that allows anyone to participate, validate transactions, and access the blockchain’s ledger. Public blockchains are highly secure due to their distributed nature, and they offer transparency, immutability, and resistance to censorship. They are the foundation for cryptocurrencies like Bitcoin and Ethereum, enabling decentralized applications (dApps) and smart contracts. While they provide broad access and are fully decentralized, public blockchains may face challenges with scalability and transaction costs due to the high number of participants validating and recording transactions.