A kind of system is a way of organizing or classifying something. Metric is a system of measurement based on the meter, the base unit of length in the International System of Units. SOLAR is a system that uses energy from the sun to generate electricity. MERIT is a system of rewards and punishments based on one's performance. POLITICAL is a system of government by the people, for the people. CASTE is a system of social stratification based on hereditary status. DECIMAL is a system of numbers based on powers of 10. Eco is a system of living in harmony with nature. IMMUNE is a system of defense against foreign substances in the body. STEREO is a system of sound reproduction using two or more channels. Twoparty is a system of government in which two major POLITICAL parties dominate elections and hold power.