New York City Subway nomenclature

New York City Subway nomenclature is the terminology used in the New York City Subway system. The modern system was constructed and operated by multiple companies, which were unified into a single system in 1940. The process of integrating multiple systems, as well as over a century of service changes, have lead to a complexity of conventions around station naming, directionality and the routes themselves. In particular, the New York City Subway distinguishes between lines, or individual sections of subway, and services, or train routes. Services are represented visually by grouped, color coded service bullets, which have changed significantly over time.