These are major changes that affect how the network processes new transactions. The systems that upgrade will become a new cryptocurrency. The ones that don’t will continue operating with the old protocol. This means that there are now two different cryptocurrencies. I’ll use an example to make things clearer;Imagine ten cars driving down a road. One car decides to turn right. Four of the other cars think that’s a great idea so they turn right as well. The remaining five cars think turning right is a bad idea, so they keep going straight on. Instead of one group of cars going in a single direction, you now have two groups going in separate directions!