Fiber becomes yarn, yarn becomes greige fabric, and greige is dyed or printed, then cut, sewn, finished and packed. Many of those steps go out as job work (CMT, printing, washing) to subcontractors who return the goods days or weeks later. In India, goods sent to job workers are reported under GST on Form ITC-04.
Every style explodes into colors and sizes, and a size curve sets how many of each size to make. Fabric is the largest single cost in a garment, so marker efficiency and cutting decide margin. Dyeing happens in lots, and shade lots must not mix within an order. Sewing-line plans are built from the standard allowed minutes (SAM) of each operation.