I saw a map of undersea internet cables the other day and it’s crazy how many branches there are. It got me wondering - if I’m (based in the UK) playing an online game from someone in Japan for example, how is the route worked out? Does my ISP know that to get to place X, the data has to be routed via cable 1, cable 2 etc. but to get to place Z it needs to go via cable 3, 4?
The simplest explanation is that my computer doesn’t know where to go for everything but does know where to go to get answers. It sends its traffic to the place that will know where to send things. Rinse and repeat until you finally hit the place you wanted to go.
A more complete answer if you chase everything down is the traceroute manpage.