A firefighter is a first responder trained in firefighting, primarily to control and extinguish fires that threaten life and property, as well as to rescue persons from confinement or dangerous situations. Male firefighters are sometimes referred to as firemen (and, less commonly, a female firefighter as firewoman).

The fire service, also known in some countries as the fire brigade or fire department, is one of the three main emergency services. From urban areas to aboard ships, firefighters have become ubiquitous around the world.

The skills required for safe operations are regularly practiced during training evaluations throughout a firefighter's career. Initial firefighting skills are normally taught through local, regional or state-approved fire academies or training courses. Depending on the requirements of a department, additional skills and certifications may also be acquired at this time.

Firefighters work closely with other emergency response agencies such as the police and emergency medical service. A firefighter's role may overlap with both. Fire investigators or fire marshals investigate the cause of a fire. If the fire was caused by arson or negligence, their work will overlap with law enforcement. Firefighters may also provide some degree of emergency medical service.