The Silver Line, also known as the Cotton Belt Rail Line, is an under construction 26-mile (42 km) hybrid rail line traversing Collin, Dallas, and Tarrant Counties in the U.S. state of Texas operated by Dallas Area Rapid Transit (DART). The line will provide service from Dallas's northeast suburbs of Plano, Richardson, and Addison to Dallas/Fort Worth International Airport Terminal B.

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.