Jumping is a strategy in the World Map which involves constantly taking over outposts and moving your main yard to them. It is a good strategy however it also means that you will not be able to get as much empire points or outposts as otherwise. It can be a great harm to some alliances though. A way to minimize damage caused by jumpers is to try not to take over too many outposts in one place.
Jumpers are usually people who get hired for the sake of destroying Empire builders,great jumpers can defeat a huge empire within hours.Also,most jumpers uses shiny for stuff in the Combat sector of the General Store.