Balancer is a non-custodial portfolio manager and automated market maker built on Ethereum that pools up to eight different tokens for users to trade. These Balancer pools are self-balancing weighted portfolios with specific triggers, and the Balancer protocol allows all Ethereum accounts to add tokens to existing public pools or create their own private pools. The resulting market system creates a structure resembling an Exchange Traded Fund (ETF), which continuously rebalances and pays both trading fees and BAL tokens to liquidity providers.