Brotherhood of Steel iconography

The iconography of the Brotherhood of Steel is built around its emblem, featuring gears, a sword and wings. This iconography is widely used to decorate their facilities, tag armor and equipment, and as part of markers identifying their territory. The gears represent their engineering knowledge, the sword is their will to defend themselves, the wings represent the uplifting hope that the acquisition of lost technology represents for mankind's salvation following the devastation of the Great War, and the circle represents the fraternal unity that makes the organization a true brotherhood.

Another interpretation is that the Brotherhood's symbol represents each of the organization's different orders. The sword represents the Paladins, the wings represent the Elders (the "wings" control the movement of the sword), the large gear represents the Knights, and the two smaller gears represent the Scribes and the Initiates, whose services keep the Knights supplied with the information and the manpower required to get their jobs done.

Insignias
The Brotherhood insignia has evolved throughout the years and while it has retained its general appearance, the number of cogs on the gears, their facing, and basic color scheme have varied between iterations. The standard is nine cogs on each wheel, at times facing interchangeably, as both left- and right-sided have been in use at the same time, specifically within the Appalachian chapter between approximately 2082 and 2095, later with the Brotherhood First Expeditionary Force in 2103, as well as the Mojave chapter in 2281.

Flags
The Brotherhood has also used a variety of flags. Most simply feature the Brotherhood insignia over a flat-color field. One, featuring a white Brotherhood insignia over a set of 13 red and white stripes, was flown by the Lyons' Brotherhood of Steel in 2277.

Merchandise
Bethesda uses a variety of Brotherhood symbols in merchandise for the Fallout series; some of these designs do not appear in the games themselves.

Non-canon
These are variants of the Brotherhood's symbols used exclusively in materials deemed non-canon by Bethesda.

Behind the scenes

 * The flag with the sword, gears, wings, and stripes was first used in Fallout 3, as a low resolution asset flown over the Citadel. When extracted, the texture can be recreated to produce the flag on the right. However, it is readily apparent that it's meant to be a combination of the 13 stripes on the United States national flag (representing the 13 founding colonies), with the canton in the upper left replaced by a mono-colored Brotherhood emblem. This interpretation is supported by the official merchandise (where a full size flag uses the red-and-white version) and Fallout 76's Nuclear Winter mode, where the Brotherhood of Steel minigun paint has a decal depicting this version of the flag.
 * However, the flag used for these is a slightly erroneous recreation that was first posted on this wiki shortly after the game's release. While generally accurate, the sigil was oversized (terminating on the last, rather than penultimate stripe) and placed in a round field, whereas the sigil on the Citadel flag was placed with a stroke blending effect applied that gave it a rounded appearance. Curiously, the original asset is based on a thirteen stripe design, with a burlap filter applied and the sigil placed over the filter with a stroke effect applied, masking part of the burlap filter. This version was subsequently used as the basis for the Brotherhood of Steel flag in official Bethesda merchandise.