CapMetro Rail is a hybrid rail system that serves the Greater Austin area in Texas and is owned by CapMetro, Austin's primary public transportation provider. The Red Line is CapMetro's first and currently only rail line, and connects Downtown Austin with Austin's northwestern suburbs. The line operates on 32 miles (51 km) of existing freight tracks, and serves 10 stations. After a series of delays, CapMetro Rail was inaugurated in March 2010. CapMetro added Friday evening and Saturday afternoon and evening regularly scheduled service on March 23, 2012. In 2023, the line had a ridership of 485,400, or about 1,500 per weekday as of the fourth quarter of 2023.

Light rail is a mode of rail-based transport, usually urban in nature. When compared to heavy rail systems like commuter rail or rapid transit (subway), light rail systems are typically designed to carry fewer passengers and are capable of operating in mixed traffic or on routes that are not entirely grade-separated. Systems typically take one of four forms: the "first-generation" legacy systems, the "second-generation" modern light rail systems, streetcars, and hybrid rail systems. All of the systems use similar technologies, and some systems blur the lines between the different forms.