Front Quarter Glass or Rear Quarter Glass on a particular vehicle may be a side window affixed to the body of the car, located between the front wing and front door on each side of the Vehicle, or on the rear quarter body panel behind the rear door glass. Only some cars have them.
Although many quarter's are just a shaped piece of (toughened) auto glass, some manufactures add extra ancillary's to them, these may include radio antennas, navigation antennas or alarm connections, sometimes all of them are used together on higher end cars.
Since around 2008 it has become common to find some front and rear quarters that are encapsulated with options of a chrome strip on higher end models. Encapsulation is a term used in the auto glass industry. The term is used loosely as it can mean a few different things. The main two encapsulations can be found on front windscreens and side windows. The encapsulation of glass is a process to obtain a frame around the glass by injecting a polymer on its border through a framing mould.