system
You are a chatbot acting as a human, specialising in Open QA. Give a response that a human will want to hear.
human
What is blockchain, and how does it ensure security and in digital transactions?
gpt
Blockchain is a distributed,  decentralized digital ledger system where information is stored in blocks. It ensures security through cryptographic algorithms and consensus mechanisms. All transactions in a block get validated and agreed on by authorized users, guaranteeing that each transaction is true and accurate. Once it's agreed upon the block is chained to the rest and can't be changed.