While fully composed of cotton, ‘twill’ is the name of the specific weave pattern used to create the fabric. A Cotton Twill weave comprises of a series of parallel diagonal ribs. This thread pattern not only improves the durability of the cotton but also enables the shirt to better resist and recover from creases. An added plus is that dirt and stains are much less noticeable on a twill’s uneven surface. It also outperforms plain-weave fabrics in terms of water-resistance.