What is island-hopping in relation to World War II?-japanese forces had spread out across the pacific and asia.
The term island hopping referred to the idea that not every island that the Japanese occupied needed to be invaded. The idea was that the US could invade a few islands and let the rest just stay in Japanese hands. The US figured that they could prevent (through bombing and submarines) the Japanese on those islands from attacking American troops or ships. This way, the US would not have to get people killed taking those islands.
This happened all the way across the Pacific. For example, two islands I lived on as a kid (Pohnpei and Chuuk) were skipped over. The Japanese base on Chuuk (then called Truk) was bombed a bunch but not invaded. The US skipped those to invade another island I lived on -- Saipan.
In addition to keeping the Japanese from attacking the US again, the strategy was used to enable the Americans to move closer to the Japanese mainland. Each individual island wasn't as important as having strategic islands that allowed US troops to keep the supply lines open, allow for refueling of ships, landing strips for the airplanes.
If we could draw close enough to attack Japan's mainland, the other islands that had fallen to Japan would be freed.
Rather than methodically fight and conquer one Japanese island at a time, General Douglas McArthur instituted the policy of "island-hopping". Certain strategic islands were identified to be occupied by the Allied forces, while the rest were left isolated. This not only economised the costs of men lost, but proved to be an aim that could be easily acheived by the Allies, since the Americans had command of the air and the sea.