This document discusses different types of anonymous networks and how they provide anonymity for internet users. It introduces mix networks, peer-to-peer networks and other approaches that aim to hide a user's identity and communications. The document outlines various anonymous network architectures including centralized high-latency systems, centralized low-latency systems, and distributed/pseudo-distributed networks. It also discusses some of the challenges of providing anonymity including various attack approaches adversaries may use to try and de-anonymize networks.