Soft Forks vs. Hard Forks


Once in a while, we get big news about a blockchain fork nearing. If you remember, a long-anticipated Ethereum fork happened recently, and more forks are expected to happen in the future for sure.

But what does a fork mean? Is there a difference between a soft and a hard fork, or any other forks for that matter? What are they?

Don’t skip a line and read on!

Fork: the definition

A fork can be defined as a modification of any given open-source code. As it often happens, the modified, or forked, code is similar to the original. It contains modifications and, in certain cases, can co-exist with the original code.

Why would a code be modified? Mostly, to implement an important change in the code. It can also be used for testing or creating new assets. However, a fork sometimes happens automatically when not all the nodes in the chain are replicating the same information.

How soft is a soft fork?

A soft fork is a ‘mild’ method of upgrading a blockchain, whereas the two codes – the original and the one – can co-exist with each other freely. It can be compared with a software upgrade that is compatible with all the previous versions.

Soft forks do not require upgrade of nodes on the network to maintain consensus as all the blockchain blocks follow both the old set of consensus rules as well as the new ones. But the blocks produced by nodes following the old set of consensus rules will violate the new set of rules.

This means that for a soft fork to work, a majority of miners must recognize the new set of consensus rules. Given that such majority is reached, the new fork will be adopted for use and recognition.

Go hard or go home!

A hard fork is a permanent modification that cancels all the previous code versions. The older versions must be disabled as if they’re still running, it may lead to confusion and possible network error.

Unlike soft forks, hard works require all network users to update their versions to conform with the new set of rules.

Hard forks can also be divided into subcategories, but let’s focus on forks in general for now and dedicate another blog post to their subcategories.

Are there any other forks?

Sure! There are temporary forks.

Temporary forks occur when several miners discover a block at the same time, so that there are two competing blockchains.

Temporary forks are resolved in proof-of-work systems, e.g., Bitcoin*. Miners will then select a chain, and the longest blockchain is considered to be the true blockchain. Sadly, the shorter chain is simply out.

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We hope this blog post was useful!

The CoinMetro Team