A public blockchain is a decentralized, permissionless network where anyone can join, verify transactions, and access data. Examples include Bitcoin, Ethereum, and Solana. These networks offer transparency, immutability, and trust through consensus algorithms like Proof of Work or Proof of Stake. Public blockchains support applications such as cryptocurrencies, NFTs, DeFi, and smart contracts. Their openness fosters innovation and decentralization but may come with scalability and privacy trade-offs. Ideal for open ecosystems, public blockchains empower global participation and redefine trust in digital transactions.