The FOAM Map uses multiple smart contracts to enable a decentralized map without a central authority or single point of failure. 

Each time tokens are transferred between contracts there’s a small fee charged by the Ethereum network, called gas, that fluctuates depending on how busy the network is at that time. 

Approved FOAM and Voting Credit allow for your wallet to transfer to 2 different smart contracts. Doing this in advance helps to avoid more expensive gas and allows for fewer MetaMask confirmations and fewer chances that something can go wrong.