POY stands for Partially Oriented Yarn (POY). It is the main form of polyester yarn, also known as polyester preoriented yarn. The yarn made of polyester sheet into continuous filament by melt spinning or made directly from PTA and MEG is called partially oriented yarn. These types of filament fibers are usually low in strength but have high elongation.

Some directional yarn has semi-dark POY, full dark POY, bright POY and other different gloss. In bright POY, the glow is mainly due to the cross section of the filament. Dye dyeing technology is mainly used for partially oriented yarn dyeing. This is because the dyeing technology is more efficient and the dyeing properties are more uniform. Through machining, some directional yarns can also be made into deformed yarns. These textured yarns are called stretch textured yarns (DTY).