Portable fire extinguishers are required in certain occupancies and must be visually inspected monthly and undergo annual maintenance. They have limitations and should only be used on small, incipient fires. There are different classes of extinguishers that are suited to different types of fires. To operate an extinguisher, one should remember the PASS acronym: Pull, Aim, Squeeze, Sweep. Grease fires require a different approach than other fires.