Wildfires are large, uncontrolled fires that spread quickly through forests, grasslands, or dry areas. They can start from natural causes like lightning or from human activities, such as leaving a campfire unattended. Wildfires destroy plants and animals’ habitats and can produce thick smoke that makes it hard to breathe. The severity of a wildfire is measured by its size (in acres burned) and the speed at which it spreads. Firefighters work hard to control these fires and protect people and wildlife. To prevent wildfires, never play with matches or fire and always follow safety rules when camping.