# Wildfire Frequency Occurrence A **wildfire** is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation starting in rural and/or urban areas. Some forest ecosystems in their natural state depend on wildfire. Depending on the type of vegetation present, a wildfire can also be classified more specifically as a bushfire (in Australia), desert fire, grass fire, hill fire, peat fire, prairie fire, vegetation fire, or veld fire. The "wildfire frequency occurrence" layer refers to the number of times a wildfire is detected using satellite images. The number is returned as **‰** (per mill): $$ f(x) = (x/ X\_{total})\*1000 $$ f(x) is the returned number, x is the number of observed wildfires, Xtotal is the total number of observation for the specific area.