The Ethereum upgrade "London" coming in 9 days will be a "hard fork" and I found out what that means so you don't have to.

What is a Hard Fork?

A hard fork is when nodes of the newest version of a blockchain no longer accept the older version(s) of the blockchain; which creates a permanent divergence from the previous version of the blockchain.

Adding a new rule to the code essentially creates a fork in the blockchain: one path follows the new, upgraded blockchain, and the other path continues along the old path. Generally, after a short time, those on the old chain will realize that their version of the blockchain is outdated or irrelevant and quickly upgrade to the latest version.

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Hard Fork Illustration

In a hard fork, holders of tokens in the original blockchain will be granted tokens in the new fork as well, but miners must choose which blockchain to continue verifying.

A hard fork can occur in any blockchain even Bitcoin (where hard forks have created Bitcoin Cash and Bitcoin SV, among several others or Ethereum classic from a previous upgrade)

"Well if there's a hardfork isn't there also soft fork?" Yes that's exactly right.

Hard forks and soft forks are essentially the same in the sense that when a cryptocurrency platform's existing code is changed, an old version remains on the network while the new version is created.

With a soft fork, only one blockchain will remain valid as users adopt the update. Whereas with a hard fork, both the old and new blockchains exist side by side, which means that the software must be updated to work by the new rules. Both forks create a split, but a hard fork creates two blockchains and a soft fork is meant to result in one.

For example, a block size decrease can be implemented by soft-forking. However, doing so doesn’t automatically disconnect you from the network. You still communicate with nodes that aren’t implementing those rules, but you filter out some of the information they pass you.

Edit: This hardfork requires no action for anyone who is holding ETH (Except for node operators). You can keep your Ethereum where it currently is.

Sources:

• https://www.investopedia.com/terms/h/hard-fork.asp
• https://academy.binance.com/en/articles/hard-forks-and-soft-forks
• https://coinmotion.com/what-is-the-ethereum-london-hard-fork/