The term 'Trains in Chicago' can be summarized by the three letter acronym ELS, which stands for the Chicago Transit Authority's elevated train system. The CTA's elevated train system is a network of rapid transit lines that serve the city of Chicago and its surrounding suburbs. The system consists of eight lines, including the Red, Blue, Brown, Green, Orange, Pink, Purple, and Yellow lines. The ELS is one of the most efficient and reliable public transportation systems in the United States, providing millions of commuters with a safe and convenient way to travel throughout the city.