New York City Subway nomenclature is the terminology used in the New York City Subway system as derived from railroading practice, historical origins of the system, and engineering, publicity, and legal usage. Important terms include lines, or individual sections of subway, like the BMT Brighton Line; services, like the B, which is a single train route along several lines; and stations, such as Coney Island–Stillwell Avenue, which connects multiple lines and services. Lines and services on the New York City Subway are often confused with each other. Lines are physical train tracks, while services are the routes that use the tracks. This distinction is also made on other systems, including the Washington Metro and historically Taipei Metro, although the exact terms used differ. Characteristics Each section of subway has three identifying characteristics, line, service and color. Subway lines The most constant is the line, the physical structure and tracks that trains run over. Each section of the system is assigned a unique line name, usually paired with its original operating company or division: Brooklyn–Manhattan Transit Corporation (BMT), Interborough Rapid Transit Company (IRT), Independent Subway System (IND). For example, the line under Eighth Avenue is the IND Eighth Avenue Line. Some lines have changed names (and even divisions), but this happens relatively infrequently. Public usage of the line names varies widely, although the MTA's public usage of trunk names has increased since 2012, especially on Fastrack signs. Internally, the MTA also uses the names, both for legal reasons and to describe lines, services and locations without ambiguity. Although the three major subway systems are now unified, the terms BMT, IRT and IND are still used in line, structure and building descriptions and capital contract specifications. However, the names of the former companies are no longer used by much of the general public. Service designations Each operating service or route is assigned a letter or number. This is a path that the train service uses along the various lines. These are the most familiar names among the public, but may change frequently during construction or as services are rerouted to make best use of the network. Former IRT services (now known as A Division) are assigned numbers, and former BMT and IND services (now known as B Division) are assigned letters. Prior to consolidation under city ownership in 1940, the BMT routes were also assigned numbers. As track connections were built between