What are the three types of vacuums?

What are the three types of vacuums can be answered in two common ways, either three main types of vacuum cleaners for home or three categories of vacuum pressure levels. For household vacuum cleaners, three most common types are upright vacuums, canister vacuums, and stick vacuums. Upright vacuums are single unit standing vertically with brushroll at base, good for deep carpet cleaning and large areas. Canister vacuums have separate canister body with motor and dustbin connected by hose and wand, more maneuverable for hard floors, stairs, and upholstery. Stick vacuums are lightweight, often cordless, slim design good for quick cleaning and small spaces. Some include robot vacuums as third type instead of stick, so three types could be upright, canister, and robot. For scientific vacuum classification by pressure, three broad types are low vacuum with pressure down to 25 torr, medium to high vacuum from 25 torr to 1e-9 torr, and ultra-high vacuum below 1e-9 torr, each requiring different pumps. So when asking three types, most people mean upright, canister, and stick or robot for home cleaning.