The feemarket module is an implementation of the Additive Increase Multiplicative Decrease (AIMD) EIP-1559 feemarket. More information about the implementation can be found here.
More information about upgrading your chain to x/feemarket can be found in our dedicated guide.
Wallets, relayers and other end-users should refer to our guide for using dynamic fees for transaction submission.
A full specification for x/feemarket can be found here.