A firefighter (also known as a fireman) is a rescuer extensively trained in firefighting, primarily to extinguish hazardous fires that threaten property and civilian or natural populations, and to rescue people from dangerous situations, like collapsed or burning buildings or crashed vehicles. In some areas, they are also trained in Emergency Medical Services (EMS) and operate ambulances in addition to being a firefighter.

The complexity of modern industrialized life with a greater prominence of hazards has created an increase in the skills needed in firefighting technology and a broadening of the firefighter-rescuer's remit. The fire service, or fire and rescue service, also known in some countries as the fire brigade or fire department, is one of the three main emergency services. Firefighting and firefighters have become ubiquitous around the world, from wildlands to urban areas, and aboard ships. According to Merriam-Webster's Dictionary, the English word firefighter has been used since 1903. In recent decades it has become the preferred term, replacing fireman, since more women serve as firefighters, and also because the term fireman can have other meanings, including someone who sets, stokes, or tends fires, especially in designated fireplaces – the opposite of the firefighting role.