Pokestops and gyms are a vital part of Pokemon Go. You can get resources like pokeballs, potions and reviews from them, you can battle pokemon and you can earn pokecoins at gyms by placing your pokemon in a gym. Having stops and gyms in your area is vital when playing pokemon go.
Trainers who have reached level 37 can submit pokestops. Real world objects that meet the criteria can be submitted to become a pokestop.