Terrestrial planets are rocky and solid planets that are similar in composition to Earth. They are typically found in the inner regions of solar systems and are characterized by their solid surfaces, dense cores, and relatively thin atmospheres. Terrestrial planets are believed to have formed through the accretion of solid material in the early stages of a solar system's formation. Some examples of terrestrial planets in our own solar system include Mercury, Venus, Earth, and Mars. Research in this area focuses on understanding the geology, chemistry, and physical processes that shape terrestrial planets, as well as characterizing their atmospheres and potential habitability.