There are two distinct tiers within the British Army’s rank structure - officers and other ranks.
Officers are at the top of the hierarchy. Their ranks indicate that they hold positions of authority, granted through a commission - a formal document of appointment signed by the monarch.
Other ranks are the enlisted soldiers of the army. They do not have a commission and they do not hold positions of high command. However, separate tiers of authority - warrant officer (WO) and non-commissioned officer (NCO) - exist within their rank structure.
All soldiers’ ranks are denoted by a title and a set of insignia. Officers usually wear their insignia on their shoulders or chest. Other ranks wear theirs on their sleeves.
Field marshal is the highest rank in the British Army. Throughout the 20th century it was reserved for army and army group commanders in wartime, and retiring Chiefs of the General Staff. Peacetime promotions to the rank of field marshal have now been discontinued.
Insignia: Two crossed batons in a wreath beneath a crown
A brigadier commands a brigade in the field or holds a senior staff appointment. Originally, the rank was known as brigadier-general, the lowest general officer rank, but since the 1920s it has been a field officer rank.
Insignia: Three stars beneath a crown
Colonels normally serve as staff officers (responsible for the army's administrative needs) at divisional level and above or in command of ad hoc groupings at sub-brigade level.
Insignia: Two stars beneath a crown
The rank of colonel should not be confused with the colonel of a regiment. The latter role is usually performed by a retired general officer who has responsibility for the protection of a regiment’s interests. This dates back to the 17th century, when colonels owned and equipped their regiments.
A lieutenant colonel commands an infantry battalion, artillery regiment or cavalry regiment. They are responsible for the unit in the field and when stationed in barracks.
Insignia: Star beneath a crown
A captain is in charge of a company or serves as its second-in-command.
Insignia: Three stars
The lowest commissioned officer rank in the British Army, commanding a platoon or troop.
Insignia: One star
This is the senior non-commissioned rank, with specialist roles in the technical and non-combatant services; and in the combat and combat-support arms, responsible for discipline within the unit, and in war for its ammunition resupply and prisoner handling. Appointments include conductor and regimental sergeant major.
Insignia: Royal coat of arms, sometimes surrounded by a wreath (depending on appointment)
A WO2 has similar roles and responsibilities to WO1, but at a sub-unit level (below regimental). Appointments include company sergeant major and squadron sergeant major.
Insignia: Crown, sometimes surrounded by a wreath (depending on appointment)
The thing that distinguishes officers from other ranks is a commission. Warrant officers do not have a commission. Instead, their authority is granted through a warrant. Warrant officers must also be promoted to their position from a non-commissioned officer rank, like sergeant.
This is a non-commissioned officer rank with specific duties such as supply within the sub-unit (known as company/squadron quartermaster-sergeant - CQMS/SQMS). In infantry battalions a CQMS is called a colour sergeant
Insignia: Three chevrons beneath a crown
This is the senior enlisted soldier within a platoon or troop, acting as a second-in-command. Some also have specialist roles. In the Household Cavalry the title corporal of horse is used.
Insignia: Three chevrons
In most units a corporal commands a section. A corporal in the Royal Artillery is called a bombardier, and in the Guards lance sergeant.
Insignia: Two chevrons
This is the lowest rank of non-commissioned officer. A lance corporal usually serves as second-in-command of a section. It is also a rank held by specialists such as clerks, drivers, signallers, machine-gunners and mortarmen. A lance corporal in the Royal Artillery is called a lance bombardier.
Insignia: One chevron
Private is the lowest rank of trained soldier. Various regiments and corps have equivalent ranks such as trooper, gunner, guardsman, sapper, signalman, fusilier, craftsman and rifleman.