The Earth's lithosphere is divided into several parts known as tectonic plates. These plates are large, rigid pieces of the Earth's crust and uppermost part of the mantle. The number of plates is not fixed, but rather constantly changing due to the process of plate tectonics. Currently, there are about 7 major plates and several smaller ones that make up the Earth's lithosphere. The major plates include the Pacific Plate, North American Plate, Eurasian Plate, African Plate, Antarctic Plate, Indo-Australian Plate, and South American Plate. These plates interact with each other along their boundaries, which can result in geological events like earthquakes, volcanoes, and the formation of mountain ranges.