A smoke bomb (煙玉, kemuridama) creates a cloud of smoke when it detonates. It may look like small spheres wrapped in paper or they can be more conventional canisters. Smoke bombs are typically used to blind opponents and make them easier to attack. Alternatively, ninja can use smoke bombs on themselves so that opponents cannot see what they are doing.
Smoke bombs are not limited to actual smoke, and in fact can contain any sort of gas, such as poison or a sleeping agent. In Kakashi Retsuden, Kakashi Hatake uses a special smoke bomb that dulls the senses of those caught in it, making them easier targets for genjutsu.