A basic understanding of the behavior and characteristics of fibres is helpful in providing safe handling and treatment of textiles. Museum staff should be aware of the causes of deterioration in order to effectively care for collections. This note provides an introduction to the four natural fibres most often present in textile collections. It is strongly recommended that curators of textile collections supplement their knowledge and understanding of fibres by consulting, among others, the publications listed in this note. Basic information on fibre group identification can be obtained through simple feel and burn tests as outlined in the books recommended. However, for the most definitive identification of a fibre, a polarized light microscope is required.