What are these and of what importance are they?
Are there any other pillars in a vehicle?
Do all vehicles have all the pillars?

What Are Pillar

Pillars are vertical supports on a vehicle. They are located around all the glass on an automobile. They are important for holding glass in place and adding structural integrity to a vehicle, primarily the roof.

The "A" pillar holds the windshield in place.They are the ones you see as you look straight at the car from the front. Take a look at this representation below

" B " pillars start where the driver and passenger-side windows end as you look backward along the length of the car.

" C " pillars hold the sides of your car's rear window in place.

Note: Some cars also have a D pillar, such as estate cars for example. D pillars hold the sides of the rear window of the car in place and can also sometimes serve as a housing for the rear lights like indicators, brakes and alike

Why They Are Important

Without pillars, the glass on its own would not be able to support the weight of the cars roof. They provide a firm structure to the top of the car so that you can roll your car windows down, or even carry weight (usually up to around 100kg on most modern cars) on the roof using something like a roof rack. They provide a good base for the windows for the car to be installed.

Also, another point is that if you have a center console on the roof of your car, such as a light or electric sunroof controls then all of the cables for these interior luxuries must be routes through one of the pillars (normally the A pillar, but again this depends on the car).

Do All Cars Have Pillars?

No. For any car that doesn't have a roof, there is no need to have pillars to support anything.

NB: Some parts of this piece was culled from the internet.