A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area.

Other names such as brush fire, bushfire, forest fire, grass fire, hill fire, peat fire, vegetation fire, veldfire and wildland fire may be used to describe the same phenomenon depending on the type of vegetation being burned.

A wildfire differs from other fires by its extensive size, the speed at which it can spread out from its original source, its potential to change direction unexpectedly, and its ability to jump gaps such as roads, rivers and fire breaks.

Wildfires are characterized in terms of the cause of ignition, their physical properties such as speed of propagation, the combustible material present, and the effect of weather on the fire.

Wildfires occur on every continent except Antarctica.

Wildfires can cause extensive damage, both to property and human life, but they also have various beneficial effects on wilderness areas.

Some plant species depend on the effects of fire for growth and reproduction, although large wildfires may also have negative ecological effects.