How many kingdoms are in the modern system of classification?

According to modern classification system, all organisms can be divided into three domains (archaea, bacteria, and eukarya) and six kingdoms (archaebacteria, eubacteria, protista, fungi, plantae, and animalia.

Five kingdoms

When Linnaeus first described his system, he named only two kingdoms - animals and plants. Today, scientists think there are at least five kingdoms - animals, plants, fungi, protists (very simple organisms) and monera (bacteria).