What are gypsies and travlers ? how come they look poor but rich?

What are gypsy why are they called travelers what do they do how do they live how come their life style looks poorly but at the same time they have a lot how do they make those huge expensive wedding? Why are their wedding and dress style bring so much attention they look like costumes and exagerate? What do they live for how do they live ? Please help its like so intrsting