The two-color symbol that became McDonald's famous logo is the Golden Arches.
The arches originated as architectural features of early McDonald's restaurants. Architect Stanley Clark Meston designed the first restaurant with two tall yellow arches, one on each side of the building, making the roadside locations visible to passing motorists. The arches were initially part of the building design rather than a standalone corporate mark.
In the early 1960s, the arches were combined into the familiar stylized “M.” The resulting symbol became one of the world's most recognizable brand marks and was used widely on signs, packaging, advertising, and restaurant buildings.
A common mix-up is assuming the logo was designed as an abstract letter M from the beginning. Its history is more literal: it developed from physical yellow arches attached to McDonald's restaurants. The name “Golden Arches” remains the standard term for both the architectural forms and the emblem derived from them.