Peer-to-Peer (P2P) topology refers to a network model where each user or node in a crypto system can interact directly with other users without going through an intermediary or central server. In this system, each user has an equal role and can act as a sender, receiver, or even a service provider in the transaction.

Essentially, P2P topology means that there is no single entity that controls the entire network or system. For example, in crypto networks like Bitcoin or Ethereum, transactions between users can be made directly, and the information needed to validate the transaction is shared across the network through decentralized consensus.