Felt is a non-woven cloth that is produced by matting, condensing and pressing woolen fibres. While some types of felt are very soft, some are tough enough to form construction materials. Felt can be of any colour, and made into any shape or size.
Felt is made by a process called wet felting, where the natural wool fibre is stimulated by friction and lubricated by moisture (usually soapy water), and the fibres move at a 90 degree angle towards the friction source and then away again, in effect making little "tacking" stitches. Only 5% of the fibres are active at any one moment, but the process is continual, and so different 'sets' of fibres become activated and then deactivated in the continual process