What is Snowball Consensus Mechanism (Avalanche)?

Snowball is Avalanche's proprietary Proof-of-Stake (PoS) consensus mechanism. Snowball requires validator nodes within a subnet to repeatedly query each other to determine the validity of network transactions until they reach consensus. Snowball is the most advanced portion of Avalanche's consensus mechanism which is a combination of Avalanche's Directed Acyclic Graph (DAG) architecture, the system's Slush consensus (single-decree consensus), and Snowflake (Byzantine Fault Tolerance-based) mechanisms.