B57

B57 is a designation used in several unrelated domains. The most widely recognized reference is the Martin B-57 Canberra, a US-built bomber developed from the British English Electric Canberra. Production and first flight occurred in the mid-1950s, with the aircraft serving in the United States Air Force and in the air forces of several allied nations. The B-57 was employed as a medium bomber and later adapted to other roles, such as reconnaissance, electronic warfare, and weather observation, before its retirement from frontline service in the latter part of the 20th century.

In transportation, B57 is used as an alphanumeric route designation in various local systems. For example, some cities designate a B57 bus route or a regional road with the number 57. These uses are separate from the aircraft program and vary by country and region.

As a general labeling convention, B57 can appear in product catalogs and model series across industries, serving as a serial or designation code rather than a unified standard. Because B57 lacks a single, universal meaning, the intended reference typically depends on the specific context or geographic location.

The term thus represents a multi-domain identifier rather than a single entity. When encountering B57, the surrounding context usually clarifies whether it refers to aviation, local transportation, or another classification.