According to the Merriam Webster online dictionary, a canister is "an often cylindrical container for holding a usually specified object or substance," such as a film canister. When the term "canister" is used in reference to a vacuum cleaner, the "often cylindrical container" is what houses the vacuum's motor, filter and dirt collection container.
A suction hose is attached to the canister, as are small wheels, which allow you to pull the canister behind you as you vacuum your home.
Canister vacuums are often recommended for use on hard flooring surfaces as opposed to carpeting or rugs. This is because canisters are lightweight and are less likely to scratch or otherwise damage delicate or shiny floors.
Canisters also typically have a long, thin suction hose and a low-profile suction head, allowing you to easily vacuum stairs, underneath furniture and in overhead areas such as mini blinds or drapery. Additionally, a canister vacuum's light weight makes it easy for you to maneuver and carry around your home.
Some people find that pulling a canister behind them is less convenient than pushing an upright in front of them, as canister vacuums tend to bump into furniture and walls, and their long hoses can get tangled up in furniture. Canister vacuums tend to have smaller dirt receptacles, meaning you'll have to empty them more often.
And although canister vacuums' ability to clean carpeting has improved over the last few years, it means you'll have to uninstall, install and reinstall different suction heads to clean the different surfaces within your home.
Compare and Contrast to Uprights
While canisters are generally recommended for hard floors, uprights tend to do a better job on wall-to-wall carpeting. Even though many canister vacuums now come with a carpet attachment, many people find that uprights still do a better job of cleaning carpeting.
While both models typically come with a variety of attachments, canisters' long hoses let you clean overhead areas more easily. As of 2011, canister vacuum prices ranged from around $100 to almost $1,200.
Upright vacuums showed prices ranging from around $40 to almost $850.