Class M

Also known as terrestrial planets, M Class worlds are the most commonly visited planets. They are also called Minshara Class, a Vulcan term. They are always located in the ecological region of a star where they are provided enough warmth and energy to develop and sustain carbon-based life. Their surfaces comprises a thin tectonic layer floating on a molten rock mantle and they usually have many active volcanoes. Most importantly they have plenty of liquid water necessary for life to exist. Their atmospheres contain oxygen and nitrogen with other trace gases. Life forms are nearly always present often flourishing as extensive plant and animal life. Earth is a prime example of a Class M world. Others would be Vulcan, Risa, and Bajor.