Packet switching is a method of data transmission. Data is broken into packets of data of manageable sizes. They are sent independently through different routes decided by the router. They will be reordered into a correctly sequence when they reach the destination point.
With packet switching, there is no need to tie up a single communication line. Most problems regarding busy lines can be fixed by re=reouting packets.
The router chooses the route which the packet will take, it will always choose the route with the least traffic for efficiency.
However, packets can be lost and need to be re-sent. Packet switching is more vulnerable to errors with real time streaming such as video calls or audio calls. And there is a delay when packets are being reordered at the final destination.
Hopping is a method to solve the problem of packets clogging up the system if they never reach their destination. This can happen if the packets switch between routes a lot. To overcome this, each packet has a hop number to start with, every time they reach a router, their hop number will decrease by one. When the hop number reaches 0, the packet is then deleted.