Definition: The A-pillar or A-post is the vertical support structure on each side of a vehicle's windshield, connecting the roof to the body of the car. It forms part of the vehicle's overall structural integrity and supports the roof and sometimes includes mounting points for safety restraints such as seat belts or airbags.
Usage: The A-pillar is named based on its position in the vehicle's structure, with the subsequent pillars being B-pillar (middle pillar) and C-pillar (rear pillar), each playing a role in the car's overall structural design and safety features.
