What is Soft Fork?

A soft fork is a software update of a blockchain network that is backward compatible, meaning that a piece of software which has undergone a soft fork remains interoperable with its older legacy system. This means that nodes can continue to communicate with nodes that have not upgraded. By contrast, if a blockchain undergoes a hard fork, only new blocks generated afterwards are recognized as valid. As a result, soft forks generally entail less drastic protocol changes than hard forks.