In the UK these are called
windscreen wipers.
They are the long arms on the front screen of a car (and often the rear as well) which swish back and forth to clear the screen of rain, fog droplets and other stuff (squished bugs, bird poop and the rest) in order to improve vision for the driver.
Broadly, each wiper assembly comprises two main components, the carrier and the squeegee rubber. The squeegee rubber keeps the screen clear, while the carrier arm keeps the rubber in contact with the screen. This wiper assembly is suspended from a moving arm attached to a powerful motor. When power is supplied to the motor, it starts to turn backwards and forwards in a pre-programmed way, according to the speed set by the driver. This makes the carrier arm swing back and forth, moving the wiper assembly, together with the blade across the screen.
This carrier arm is designed to swing out from the screen to allow easy access when washing the screen, or changing the wiper blades. Simply lift the whole wiper assembly away from the screen, allowing it to rotate about the pivot at the base of the arm, and it will then click into position away from the screen.
Once you have finished washing the screen, or repairing the wiper, don't forget to click it back into its normal position. Oh, and watch out the things do not poke out your eyes as you lean over the car.
The rubber blade is usually made from natural rubber extruded into a feather edge, designed to give maximum flexibility and cleaning power at the screen. Natural rubber is used because of its extreme flexibility. The problem with a feather edge is that it is especially susceptible to degradation from ozone and oxygen. A further problem with natural rubber is that it degrades quite quickly in the sunshine, so the rubber usually rots or otherwise becomes ineffective after a year or two, even in temperate climates. In harsh sunlight, the rubber rots even more quickly.
This means that you should expect to change the wiper blades on your car roughly once per year, usually as part of the pre-winter check or service.
How do I change my wiper blades?
You have two choices here. If money is really a problem, then you can simply buy replacement rubber material, and after removing the old squeegee blade from each wiper, attempt to insert a new blade in each carrier. This is difficult, fiddly, liable to snap all your nails and (IMHO) a waste of time. The squeegee rubbers cost a few £/$/€ each.
The alternative is to measure the length of the carrier structure, go to a auto parts store and buy a replacement carrier and blade. Be careful to check the blade length for your vehicle on the reference sheets near the wiper parts. This will cost you two to three times as much, but the saving in hours spent slaving over the thing is well worth it. Each carrier and blade will cost $10 - $20, depending on the length and popularity, but they should take only a few minutes to replace.
The fixing is usually a nut and bolt, so all you have to do is undo the fixing, discard the old blade and fix the new one on. It adjusts itself automatically to lie correctly on the screen, so no manual adjustments needed.
Alternative systems
You may have seen alternative wiper blades advertised with five-year guarantees. I have seen a product called tripledge, made from a material called Nordel. This is an
EPDM material, which is known to be very resistant to damage by
ozone,
UV and
oxygen. Trouble is, it is not so
flexible as
natural rubber. While I have not used these blades, I have no doubt they really would last 5 years, but I doubt they would clean the
windscreen perfectly. My guess is that they would leave streaks even when new, simply because the material is made thick and insufficiently flexible.