Major is a rank that is given for a mid-level command officer (higher than the rank of Captain and lower than the rank of Lieutenant Colonel). In Canada, it is shown by a thick bar followed by a thin bar and again by a thick bar. In Great Britain it is represented by a single crown. In the United States, it is shown by a gold oak leaf. The pay grade for the rank of major is O-4.
Canadian Air Force major insignia
World War I British Army major's rank insignia (sleeve, general pattern)
Major rank insignia for the United States Army, Air Force, and Marine Corps.