Flannel is a soft woven fabric, of varying fineness. Flannel was originally made from carded wool or worsted yarn, but is now often made from either wool, cotton, or synthetic fiber. Flannel is commonly used to make tartan clothing, blankets, bed sheets, sleepwear, and several other uses.
Flannel may be brushed to create extra softness or remain unbrushed. Brushing is a mechanical process wherein a fine metal brush rubs the fabric to raise fine fibres from the loosely spun yarns to form a nap on one or both sides. If the flannel is not napped, it gains its softness through the loosely spun yarn in its woven form.
The term "flannel shirt" is often mistakenly used to refer to any shirt with a plaid or tartan pattern. However, 'flannel' refers simply to the fabric; not all flannel shirts are plaid and not all plaid shirts are flannel.