Poplin is a lightweight, fine, and durable fabric that can be produced from a variety of natural, synthetic, or blended yarns. It has a plain weave, where the warp and weft yarns interchange one by one to create a canvas-like structure.
The 100% cotton poplin used for dress shirts is light and breathable, ranging from extra fine to dense and crisp. It holds its shape well, and hardly ever tears. This also means it does not drape easily, and has little natural stretch, so it is optimal for sharply tailored styles that are not too tight, or lightweight, loosely fitted casual shirts.
Like most plain weave fabrics, cotton poplin does crease quite a bit. Poplin shirts should be washed at 40°C, and ironed while still a bit damp for best results.