解释硬分叉和软分叉之间的区别。如果您无法翻译，请保持原句不变。

Hard and soft forks are needed for the long-term success of a blockchain network. They allow many updates in a decentralized system even if there is no central authority. While both forks form a split, in a soft fork only that blockchain remains valid. However, a hard fork causes two blockchains to exist side by side, and the former is abandoned by users.

Fork on cryptocurrencies is based on forking the blockchain. It is also often referred to as a hard fork.

A fork happens on cryptocurrencies when two blocks are forked at approximately the same time and it is impossible to tell which blockchain is dominant. As more blocks are discovered, the longer chain becomes the main chain, and the shorter chain is "orphaned", i.e. mining pools stop mining it.

Forks are also done intentionally to introduce new features to the system. A fork establishes a completely new rule, incompatible with the old software. As a result, you have to update the software (client) to be able to use the system.

It may happen that some miners will not accept the changes and will stay with the old chain, while the rest will mine the new chain. Then we are dealing with a split of the network and the creation of a new cryptocurrency. An example illustrating such a situation is a fork on Ethereum (ETH) and the creation of Ethereum Classic (ETC).

Forks can also be done for purely economic purposes, a great example of which is a fork in Bitcoin resulting in Bitcoin Gold. The change was not innovative, it was to favor GPU (graphics card) miners over ASIC miners. The originators of BTG decided to leverage the popularity and huge customer base of Bitcoin to create their own cryptocurrency.

A soft fork is simply a system update that is customarily referred to as a fork. The name has become accepted among the cryptocurrency community and is used to describe protocol changes that do not require network sharing. Furthermore, making changes does not require an update because the system is backwards compatible.

A hard fork and a soft fork are both types of blockchain protocol upgrades, but they differ in how they are implemented and their impact on the network. Hard Fork: In a hard fork, the changes made to the protocol are not backward compatible. This means that nodes that do not upgrade to the new version of the software will not be able to validate new blocks on the blockchain. As a result, a hard fork can lead to a permanent split in the network, creating two separate chains with their own set of rules. Examples of hard forks include the creation of Bitcoin Cash from Bitcoin. Soft Fork: In contrast, a soft fork is a backward-compatible upgrade to the blockchain protocol. This means that nodes running older versions of the software can still validate new blocks without issue. A soft fork typically involves tightening the rules, making previously valid blocks invalid. This can lead to a temporary split in the network, but eventually, the shorter chain will be abandoned in favor of the longer one. An example of a soft fork is Segregated Witness (SegWit) implementation in Bitcoin. In summary, the main difference between a hard fork and a soft fork lies in their backward compatibility and potential impact on the network's unity.