Fibres are ubiquitous in the environment and are often transferred between shedding surfaces (Fibres: clothing, car seats, bedding, carpets, twines etc) that have been in contact; sometimes even if the contact has been fleeting.
There is potentially a significant amount of discrimination that is possible between fibres relating to their type, colour, size and other microscopic physical and chemical characteristics.
For example, two red tracksuit tops from the same manufacturer, that appear visually similar, may be differentiated from each other following a forensic examination of their constituent fibres.