Trustless is a term in blockchain and crypto technology that refers to a decentralized system where users/nodes can interact/transact without having to trust or rely on any central authority.

The concept of trustlessness is one of the key aspects of blockchain technology. With peer-to-peer architecture and advanced cryptography, blockchain allows a network of computers to reach consensus and process transactions in a decentralized manner without relying on the trust of each other or any third party (e.g. banks).

This allows the blockchain system to be highly open, neutral, transparent, and unmanipulated. Each user validates transactions and data collectively. No one party controls the network itself, everything is decided democratically peer-to-peer. This is the "trustless" principle that underlies the resilience of blockchain.