Connectionless packet switching and routing

Packets are routed to their destination as determined by a routing algorithm. The routing algorithm can create paths based on various metrics and desirable qualities of the routing path. For example, low latency may be of paramount concern and everything else is secondary, or a minimum hop count.
It's also entirely possible to have to weigh the various metrics against each other. For example, reducing the hop count could increase the latency to an unacceptable limit and some kind of balance would need to be found. For multi-parameter optimization, some form of optimization may be needed.
Once a route is determined for a packet, it is entirely possible that the route may change for the next packet, thus leading to a case where packets from the same source headed to the same destination could be routed differently.
Packet switching influenced the development of the Actor model of concurrent computation in which messages sent to the same address may be delivered in an order different from the order in which they were sent.