Abrasion Resistance: A surface filter's ability to resist damage when contact is made with larger particles and debris swept up by a vacuum cleaner.

Airflow: This is simply air movement from one location to another. Airflow determines a vacuum cleaner's ability to clean, more than any other single feature.

Airflow Recovery Capacity: ARC is a measure that refers to a vacuum filter's impact on airflow over the course of multiple cleaning cycles. The higher the ARC rating, the greater the filter's ability to maintain maximum airflow.

Air Pollution: Anything that contaminates our air or affects its composition. Polluted air can contain dust and particles, such as smoke from chimneys, carbon monoxide, and nitrogen monoxide.

Allergen: Any substance that could potentially induce an allergic reaction is referred to as an allergen. Examples of these particles and their sizes include: harmful dust (.001 to 20 microns), pollens (7-100 microns), pet dander (0.5 -10 microns) and bacteria (.03 to 30 microns).

Beater Bar: A long rigid bar or raised area on a revolving brush roll designed to push carpet away and create a rapid beating action.

Canister Vacuum Cleaner: This vacuum cleaner model contains its filtration system and suction motor in a compact housing. A cleaner head, typically featuring a beater bar and brush, is attached to the end of a hose extending out from the canister.

CleanStream™ Media: From the makers of the waterproof and breathable GORE-TEX® fabric, comes a specially processed polymer. Featuring a unique and tightly controlled array of pore sizes, CleanStream™ media allows air to pass through while stopping microscopic particles at its slippery surface. It makes an ideal filter media due to its cleanability, durability and filtration efficiency.

Depth Filter: This type of filter draws and captures particles inside the filter. Eventually the depth filter becomes clogged, reducing airflow through the filter, which can compromise its performance and potentially shorten the life of the vacuum cleaner.

Filtration Efficiency: Typically, the percentage of particles a filter is able to retain as air flows through it. This should not be confused with vacuum cleaner efficiency, which depends upon a number of factors.

Filtration System: This is the system through which air flows where particles are removed.

Final Filter: A filter that captures particles just before they exit the vacuum cleaner, including carbon dust created by the motor itself.

Gore-Tex® Fabric: The most durably waterproof, very breathable, totally windproof fabric meeting Gore's Guaranteed to Keep You Dry® standards. Created when the GORE-TEX® membrane is bonded to high-performance textiles to create laminated fabrics. Different GORE-TEX® laminates satisfy the requirements of different types of garments.

HEPA Filter: HEPA stands for High Efficiency Particulate Air and is an officially recognized standard throughout the filtration industry. It is a rating indicating that the filter is capable of retaining all particles as small as 0.3 microns in size at an efficiency rate of 99.97 percent.

HEPA-Type Filter: A marketing term meant to imply HEPA performance, but not necessarily warranting the official HEPA rating.

Microfiberglass: Microfiberglass comes in many different varieties, some of which are rated HEPA. The media consists of very small fiberglass fibers that are held together with a binding agent. Because the strength and durablility are low, microfiberglass is mainly used as a post filter to capture the dust that bypasses the primary filter. They are very good at stopping fine particles, but like paper media, will clog over time.

Micron: A unit of length equal to one millionth of a meter, or one thousandth of a millimeter. This unit is often used to describe the size of common household allergens and irritants.

Paper Bag Filter: This filter is constructed using a special paper that allows airflow to pass through while it traps as much dust and dirt as possible.

Pleated Cartridge Filter: Made from folded filter material formed into a filtration element.

Post-Motor Filter: This filter is located after the motor and serves as the final barrier between the user and the vacuum's exhaust. Depending on the vacuum's design, this may be the only filter on the unit, or the last in a series of filtration stages.

Pressure Drop: It is the increasing resistance to airflow as the filter clogs.

Primary Filter: This filter is located before the motor, inside the vacuum's casing. The purpose of the primary filter is to capture fine dust particles and to protect the motor from dust and debris that might possibly escape the vacuum bag or dust cup and return to the air.

Spunbond: Non-woven textiles are inexpensive alternatives to traditional woven fabrics. They feature various polymers randomly arranged and fused together to form a contiuous web. Most common are polyester and polyethylene. They are strong and durable but are not very good at stopping fine particles.

Suction: This is the pressure created by the motor within the vacuum cleaner that allows it to pick up dirt.

Surface Filter: This type of filter stops particles at the surface of the filter. Surface filters, such as CleanStream® filters, prevent filter clogging while preserving maximum airflow through the filter and ensuring optimum suction power with each pass of the vacuum.

Upright Vacuum Cleaner: This vacuum cleaner model houses its cleaning head, filtration system and suction motor in one self-contained unit. It has a handle that extends out of the top of it for easy pushing rather than pulling.

Vacuum: An enclosed space, such as that inside a vacuum tube, out of which most of the air or gas has been taken by a pumping action. A vacuum cleaner works by suction or the creation of a partial vacuum.

Vacuum Cleaner: A machine used for cleaning carpets, floors, upholstery, etc. by suction.

Wet/Dry Vacuum Cleaner: Also commonly referred to as a "shop" vacuum, a wet/dry vacuum cleaner is often used in workshops, home maintenance, and in industrial work sites. It can be used to clean both wet and dry surfaces.