Definition of softfork
A softfork is a variation or change in protocols on the blockchain-based network by the instructions or approval of old blocks or protocols that the new one is valid or not in a bitcoin blockchain-based application system.
Brief Explanation of softfork
The validity of a new block depends on the decision of a majority of nodes or blocks. It tells which previous block is invalid and which new block is valid.
In addition, the soft fork takes place when miners work in a chain without authorization by using non-upgraded nodes.
Many mining powers require a client to recognize softforks as a system, which makes previous nodes more valid.