Plasma is defined as an ionized gas, which occurs when matter is heated to the point where electrons are knocked off atoms. It can be found in various places, including the solar wind surrounding Earth and phenomena like solar flares and the northern lights. Plasma conducts electricity and interacts with magnetic fields, which is why astronauts experienced communication blackouts during re-entry due to plasma formation around their spacecraft. Additionally, plasma is utilized in technologies such as neon signs and fusion reactors. Overall, plasma's unique properties make it a fascinating subject in both physics and technology.