The term “trustless” describes a feature of a decentralized blockchain in which there is no requirement for users to place their trust in a third party in order to use the network. The term “trustless system” refers to a technique that allows all participants to agree on a single truth without the need for any central authority and without having to know or trust one another.
Anyone with a computer and an internet connection can take part in validating transactions on the Bitcoin network, unlike existing networks that are run by centralized banking entities like SWIFT. Every transaction is recorded on a public ledger, allowing anybody to see the entire history. Code and properly crafted economic incentives are trusted instead of one central institution.