The much-awaited new protocol of Ethereum will probably be launched on August 4 between 3:00 UTC and 17:00 UTC, with block 12,965,000.
Depending on several factors, the new release of Ethereum could be postponed by a week or two. For example, if the launch of Rinkeby’s testnet, which is scheduled for today July 7, is successful, there will probably not be any delays.
“Hoping for August 4th myself but it could be pushed out a week or two from that date depending on various factors.”
Anthony Sassano

The London hard fork is part of Ethereum’s plan to launch its proof-of-stake protocol, the long-awaited Ethereum 2.0. After a successful activation on the Ropsten and Goerli testnets, the date for the mainnet’s launch was finally decided.
The protocol update will introduce EIP 1559, which is a new fee structure that will make Ethereum less inflationary. It will also include EIP 3554 that will make mining more difficult. This will eventually help in the transition from proof-of-work to proof-of-stake.
What are forks and how do they work?
The blockchain network is open-source. This means that the code is available to everyone, and anyone can suggest different types of improvements or change it.
A fork happens when the software of distinct miners becomes misaligned, and miners, in a unanimous way, have to choose which one of these versions of the blockchain to use. If there isn’t a unanimous consensus, there will be two different blockchains.
Forks are frequently related to the issuing of new tokens. There are two ways to launch a new cryptocurrency; either to create it from the beginning, or “fork” it. When two versions of blockchain are generated and a unanimous decision to continue with only one of them, one can continue as the first token (for example Bitcoin), and the other can produce another token (how Bitcoin Cash was created).
Forks can be categorized as:
Hard forks are permanent separations from the former blockchain version. A major change is made to the software and is necessary for every user to use the updated blockchain. Those that continue running the old software won’t be integrated into the new one.
Soft forks are usually used to apply software upgrades. The new version of the blockchain is used to validate transactions. The miners that still utilize the old software will anyway see the new blocks as legitimate. But the new blockchain won’t acknowledge the non-updated nodes. For a soft fork to function, the majority of the users need to upgrade to the latest version.