At its core, a plastic airless bottle is a dispensing system that protects its contents from air exposure. Unlike a simple bottle with a pump that sucks product up through a tube, an airless system uses a mechanism to push the product out without ever letting air back in to replace it.

This is achieved through one of two main designs:

1. Piston-Type System: A flat disc (the piston) sits at the bottom of the product. As you pump, the product is dispensed and the piston rises, pushed by a base plate that moves upwards, ensuring no air gap forms.

2. Bag-In-Bottle (BIB) System: The product is sealed inside a flexible, collapsible pouch. The pump draws product directly from this bag. As the product is used, the bag collapses, again preventing air from entering.