With Ethereum's "London" hardfork coming tomorrow, I took a look at a list of all the upgrades coming with it.

On Aug. 4 at block 12,965,000, the London Hard Fork will go live on the Ethereum main network when a series of five protocol updates called EIPs (Ethereum Improvement Proposals) are deployed.

EIP 1559: This is the biggest of the upgrades and ironically the easiest to summarize. It's a proposal to make Ethereum transactions more efficient by using a hybrid system of base fees and tips to more evenly incentivize miners in periods of high and low network congestion.

EIP-3198: As a companion to EIP-1559, it adds an opcode, BASEFEE, which returns the value of the base fee for the block it is executed in. This will enable smart contracts to access this value on chain, which can help with submitting fraud proofs and creating trustless gas price derivatives.

EIP-3529: Another significant change introduced in London is the removal of gas refunds from SELFDESTRUCT and reduction of refunds for SSTORE. While the refunds were originally intended to incentivize developers to clear the state when possible, in practice they have led to an increased state size with the invention of Gas Tokens. Using these refunds, Gas Tokens can fill up the state when gas prices are low and then get refunds for the execution of transactions when gas prices rise.

EIP-3541: This is a "simple" change which lays the groundwork for broader Ethereum Virtual Machine (EVM) improvements, described in EIP-3540. This EIP will make it impossible for new contracts starting with the 0xEF byte to be deployed. Once London is live, the shortest sequence of bytes starting with 0xEF which does not match the starting sequence of existing contracts could then be reserved as a way to identify contracts which comply with EIP-3540 semantics.

EIP-3554: This proposal delays the difficulty bomb, which is a mechanism that was introduced in Ethereum to “freeze” mining as the network transitions to proof of stake. Given that the proof of stake transition is not yet ready, they have decided to delay when the bomb will “go off”. The current delay has been set to December 1st.

Sources:

• https://eips.ethereum.org/EIPS/eip-1559
• https://eips.ethereum.org/EIPS/eip-3198
• https://eips.ethereum.org/EIPS/eip-3529
• https://eips.ethereum.org/EIPS/eip-3541
• https://eips.ethereum.org/EIPS/eip-3554
• https://medium.com/ethereum-cat-herders/london-upgrade-overview-8eccb0041b41