For questions about asbestos and asbestos mitigation. Please note that questions about identifying asbestos cannot be answered on this site and are likely to be closed as off topic. Asbestos identification requires a lab test.
Asbestos is a fibrous mineral. It has been used in the past in tiles, cladding and roofing materials and as insulation primarily due to its desirable properties of heat and electrical resistance.
In the 1970's Asbestos was identified as a health and safety hazard causing serious lung disease and cancer.
For more information see: Wikipedia: Asbestos