When people talk about asbestos what they are really referring to is any type of fibrous silicate minerals used in construction. Asbestos was a popular building material from the 1940s right through until the 1980s as an insulator and fire retardant.  In the mid 1980s the effects on health became apparent and asbestos was made illegal or not commonly used in most places.
There are two types of asbestos, and they require different handling techniques.

Friable (non-bonded) asbestos is “pure”, and has not been mixed with a bonding agent.  It is quite loose and easily becomes airborne if disturbed.  Friable asbestos is most commonly found in industrial construction and rarely in homes.  Friable asbestos poses a larger risk to health than its counterpart, which is;

Non-friable (bonded) asbestos, asbestos fibers mixed with another agent.  Non-friable asbestos is commonly used as insulation in homes prior to the mid 1980s.  When bonded to another agent there is little chance for asbestos fibers to become airborne, reducing but not entirely mitigating the health risk.  In most states small amounts of non-friable asbestos are able to be removed by homeowners or general tradespeople without additional training or qualification.

Friabale Asbestos

Friable(non-bonded) asbestos is “pure”, and has not been mixed with a bonding agent.  It is quite loose and easily becomes airborne if disturbed.  Friable asbestos is most commonly found in industrial construction and rarely in homes. Friable asbestos poses a larger risk to health than its counterpart.

Non-friable (bonded) asbestos

Non-friable (bonded) asbestos, asbestos fibers mixed with another agent.  Non-friable asbestos is commonly used as insulation in homes prior to the mid 1980s.  When bonded to another agent there is little chance for asbestos fibers to become airborne, reducing but not entirely mitigating the health risk.  In most states small amounts of non-friable asbestos are able to be removed by homeowners or general tradespeople without additional training or qualification.