Base Fee for all blockchain transactions. This is a minimum fee that is adjusted based on gas usage per block. When gas usage is high, the fee increases, and when it is low, the fee decreases. Base fees are burned by the protocol rather than paid directly to the miners (or validators in the case of POA). In addition to the base fee, a priority fee can be added to a transaction as a tip to incentivize POA validators to include it in a block.