Field marshal is the second most senior military rank, ordinarily senior to the general officer ranks, but junior to the rank of Generalissimo. Usually, it is the highest rank in an army, and as such, few persons are ever appointed to it. It is considered as a five-star rank (OF-10) in modern-day armed forces in many countries. Promotion to the rank of field marshal in many countries historically required extraordinary military achievement by a general. However, the rank has also been used as a divisional command rank and also as a brigade command rank. Examples of the different uses of the rank include Afghanistan, Austria-Hungary, Pakistan, Prussia/Germany, India and Sri Lanka for an extraordinary achievement; Spain and Mexico for a divisional command ; and France, Portugal and Brazil for a brigade command.

A five-star rank is the highest military rank in many countries. The rank is that of the most senior operational military commanders, and within NATO's standard rank scale it is designated by the code OF-10. Not all armed forces have such a rank, and in those that do the actual insignia of the five-star ranks may not contain five stars. For example: the insignia for the French OF-10 rank maréchal de France contains seven stars; the insignia for the Portuguese marechal contains four gold stars. The stars used on the various Commonwealth of Nations rank insignias are sometimes colloquially referred to as pips, but in fact either are stars of the orders of the Garter, Thistle or Bath or are Eversleigh stars, depending on the wearer's original regiment or corps, and are used in combination with other heraldic items, such as batons, crowns, swords or maple leaves.