This is a very broad question, it all depends on the vacuum. you can have uprights and canister styles, two motor or single motor. Older plastic vacs had a lot more separate parts than newer ones do. The newer ones are made from simple molds.
However, I will give it my best shot.
At the base of the vacuum, you have the brush roll and its belt, the brush plate/cover, height adjuster wheels, rear rolling wheels, motor mounts, hood, motor base(part that holds everything above).
Above this, you have the motor, either direct air flow or bypass, the dirt tube, bag assembly, hard or soft, or bagless. newer machines have simple rocker switches mounted somewhere on the upper housing, older machines either have a foot switch(built in the motor) or a push rod on the upper housing that controls a rocker switch in the motor or somewhere on the housing. And then of course you have a cord.
On canister style machines, there is the main canister, which has the motor, bag and attachments. some more sophisticated machines have digital control boards that monitor motor temperature, clogs, bag fullness and motor speed. usually vacs like that have some sort of control on the electric hose handle. And lastly for the canister there is the power nozzle which has the same components as an upright's base, with the exception of the motor is usually no more than 2 amps.
In two motor systems(very similar to canister operation) there is a small motor in the base of the vacuum that can usually be turned off and on without shutting the main motor off. These machines are always designed as by-pass systems, and the motor is completely enclosed.
A vacuum cleaner has many parts, including the hose and the on and off switch. A vacuum also has a container which holds the dirt and dust that the vacuum sucks up.
Parts for a Kirby vacuum cleaner can be bought directly from the Kirby manufacturer. In addition, these parts may also be available from retail stores that sell Kirby vacuum cleaners.
For vacuum cleaner repair, one can try Sears Home Services, Oreck Store, Sobel Vacuum, Vacuum Doctore KZoo, Capital Vacuum, and S & L Vacuum Cleaner Service Repair and Parts.
Vacuum parts for Hoover vacuum cleaners can be found on the Hoover website. They have parts for a wide variety of models and you can be sure that all parts are authentic Hoover parts.
Given the history of the vacuum cleaner, the Hoover is the best choice for that trade or common name.
Master nozzie is parts get little particles in floor.
One can get parts for a 1990 Hoover junior vacuum cleaner at ransomspares or at espares. These places have many old spare parts for your old equipment and can get them replaced for you easily.
Parts for the Miele vacuum cleaner can be found in several locations. A web search will help direct you to a local parts supply or authorized repair service location.
You can order Kenmore vacuum cleaner parts without the internet from Sears Parts Direct. You can contact Sears Parts Direct by phone at 1-800-252-1698.
Daniel Hess invented the first vacuum cleaner and called it a carpet sweeper.
Vacuum cleaner spare parts can often be ordered directly from the manufacturer. The information booklet that comes with the vacuum will usually have contact information and information on ordering parts.
If parts are available (some models are no longer supported), they might be found at online vacuum parts suppliers. A good vacuum cleaner shop can be of help, too.