What is the MAIN feature that onion routing networks offer?

The main feature that onion routing networks offer is anonymity. Anonymity is the state of being unknown or unidentifiable by hiding or masking the identity or the location of the sender or the receiver of a communication. Onion routing is a technique that enables anonymous communication over a network, such as the internet, by encrypting and routing the messages through multiple layers of intermediate nodes, called onion routers. Onion routing can protect the privacy and security of the users or the data, and can prevent censorship, surveillance, or tracking by third parties. Non-repudiation, traceability, and resilience are not the main features that onion routing networks offer, as they are related to the proof, tracking, or recovery of the communication, not the anonymity of the communication. References: CISSP All-in-One Exam Guide, Eighth Edition, Chapter 4, Communication and Network Security, page 467. Official (ISC)2 CISSP CBK Reference, Fifth Edition, Chapter 4, Communication and Network Security, page 483.