A state channel is a communication channel between participants in a blockchain network, in which they can conduct transactions and exchange data outside of the public blockchain. This allows for faster, more efficient, and cost-effective transactions, as they are not required to be recorded on the blockchain, avoiding the need for multiple confirmations and reducing the overall strain on the network. State channels are often used in decentralized applications, especially in gaming and financial applications, to increase the scalability and security of transactions.