A backward-compatible protocol change where upgraded nodes enforce stricter rules without splitting the network.
In a soft fork, non-upgraded nodes still accept blocks from upgraded miners, but upgraded nodes may reject blocks that don’t follow the new stricter rules. SegWit activated via soft fork on BTC.
"A soft fork can add new script rules that only upgraded nodes enforce; old nodes continue operating without immediate disruption."
All terms and definitions may update as the Cryptionary improves.