Amp ($AMP) is an ERC-20 collateral token designed to decentralize the risk in a payment transaction and reducing the assurance cost from counterparty networks. Using specific partition strategies, Amp can enable tokens to be conditionally allocated as collateral without requiring transfers to another smart contract.
Basically, $AMP can be used as collateral when a transaction is not confirmed yet. It will be liquidated to cover the losses if consensus is not achieved, otherwise it can be released and used collateralize other transfers.
It is currently used on the payment network Flexa. To enable payment functionality, applications and communities can collectively stake $AMP on behalf of users. As incentive for supplying collateral, the entirety of network transaction revenue funds the continuous open-market purchase of Amp tokens for redistribution as network rewards.