Denim
jeans, jackets, workwear, bags
Denim is a cotton twill: the weft thread passes over and under multiple warp threads in a staggered pattern, which produces the diagonal rib visible on the fabric face. Traditionally the warp yarns are dyed with indigo and the weft yarns stay undyed, which is why denim fades unevenly and shows white at worn creases and abrasion points. Garment-weight denim runs from about 220 g/m² for a light shirting denim up to 500 g/m² or more for raw selvedge and workwear-grade cloth.
Rigid 100% cotton denim has no stretch and needs breaking in, softening and molding to the body with wear. Stretch denim adds a small percentage of elastane to the weft for comfort and recovery, at the cost of some of that structured, raw hand. Denim is dense and abrasion-resistant, which is exactly why it holds up to hard wear, but that same density means it takes a heavier needle and a longer stitch length than a lightweight cotton, and thick seam intersections (like a waistband corner) can be tough to sew through on a home machine.
Denim is the standard for jeans, jackets, and anything meant to take abuse and improve with age. Heavier weights (14 oz and up) suit structured outerwear and bags; lighter weights (under 10 oz) work for shirts and dresses where some drape is wanted. Raw (unwashed) denim will bleed dye onto skin and other fabric for the first several washes, so washing separately at the start matters.