Army Reserve (United Kingdom) in the context of "Honourable Artillery Company"

A head-mounted display (HMD) is a display device, worn on the head or as part of a helmet (see helmet-mounted display for aviation applications), that has a small display optic in front of one (monocular HMD) or each eye (binocular HMD). HMDs have many uses including gaming, aviation, engineering, and medicine.

Virtual reality headsets are a type of HMD that track 3D position and rotation to provide a virtual environment to the user. 3DOF VR headsets typically use an IMU for tracking. 6DOF VR headsets typically use sensor fusion from multiple data sources including at least one IMU.

The British Army is the land warfare force of the United Kingdom responsible for defending the UK, the British Overseas Territories and Crown Dependencies. The British Army has seen involvement in most of the world's major wars throughout history, including both world wars and was founded in 1707. As of 1 January 2025, the British Army comprises 73,847 regular full-time personnel, 4,127 Gurkhas, 25,742 volunteer reserve personnel and 4,697 "other personnel", for a total of 108,413.

The British Army traces back to 1707 and the formation of the united Kingdom of Great Britain which joined the Kingdoms of England and Scotland into a single state and, with that, united the English Army and the Scots Army as the British Army. The English Bill of Rights 1689 and Scottish Claim of Right Act 1689 require parliamentary consent for the Crown to maintain a peacetime standing army. Members of the British Army swear allegiance to the monarch as their commander-in-chief. The army is administered by the Ministry of Defence and commanded by the Chief of the General Staff.

A military reserve force is a military organization whose members (reservists) have military and civilian occupations. They are not normally kept under arms, and their main role is to be available when their military requires additional manpower. Reserve forces are generally considered part of a permanent standing body of armed forces, and allow a nation to reduce its peacetime military expenditures and maintain a force prepared for war. During peacetime, reservists typically serve part-time alongside a civilian job, although most reserve forces have a significant permanent full-time component as well. Reservists may be deployed for weeks or months-long missions during peacetime to support specific operations. During wartime, reservists may be kept in service for months or years at a time, although typically not for as long as active duty soldiers.

In countries with a volunteer military, reserve forces maintain military skills by training periodically (typically one weekend per month). They may do so as individuals or as members of standing reserve regiments—for example, the UK's Army Reserve. A militia, home guard, state guard or state military may constitute part of a military reserve force, such as the United States National Guard and the Norwegian, Swedish and Danish Home Guard. In some countries (including Colombia, Israel, Norway, Singapore, South Korea, Sweden, and Taiwan), reserve service is compulsory for a number of years after completing national service. In countries with conscription, such as Switzerland and Finland, reserve forces are citizens who have completed active duty military service but have not reached the upper age limit established by law. These citizens are subject to mandatory mobilization in wartime and short-term military training in peacetime.

The Territorial Decoration (TD) was a military medal of the United Kingdom awarded for long service in the Territorial Force and its successor, the Territorial Army.

This award superseded the Volunteer Officer's Decoration when the Territorial Force was formed on 1 April 1908, following the enactment of the Territorial and Reserve Forces Act 1907, (7 Edw.7, c.9) which was a large reorganisation of the old Volunteer Army and the remaining units of militia and Yeomanry. However, the Militia were transferred to the Special Reserve rather than becoming part of the Territorial Force. Recipients of this award are entitled to use the letters "TD" after their name (post-nominal).

The Royal Regiment of Artillery, commonly referred to as the Royal Artillery (RA) and colloquially known as "The Gunners", is one of two regiments that make up the artillery arm of the British Army. The Royal Regiment of Artillery comprises thirteen Regular Army regiments, the King's Troop Royal Horse Artillery and five Army Reserve regiments.

The Royal Armoured Corps is the armoured arm of the British Army, that together with the Household Cavalry provides its armour capability, with vehicles such as the Challenger 2 and the Warrior tracked armoured vehicle. It includes most of the Army's armoured regiments, both the Royal Tank Regiment and those converted from old horse cavalry regiments. In September 2024, it comprised fourteen regiments: ten Regular Regiments; four Army Reserve. Although the Household Cavalry Regiment (the Life Guards and the Blues and Royals) provide an armoured regiment, they are not part of the RAC.

The University Officers' Training Corps (UOTC), also known as the Officers' Training Corps (OTC), are British Army reserve units, under the command of the Royal Military Academy Sandhurst, which recruit exclusively from universities and focus on training and developing leadership. Their role is to allow university students the opportunity to undertake modules of Reserve Officer training designed to fit around their degree and to develop the leadership abilities, skills and experience of their members, which could be useful in a future career in the British Army, or skills and training that can be utilised in a civilian career. While in the UOTC, Officer Cadets will undertake the Reserve Officer Training Modules (Alpha & Bravo).

University students serving with the UOTC are personnel of the Army Reserve, and are attested and paid when on duty. They are classed as Group B (Non Deployable), whilst in the UOTC. Students undergoing service with the UOTC hold the rank of Officer cadet. Students have no obligation to pursue further service in the armed forces when they leave university and can resign from the UOTC at any time. UOTCs are led by officers and non-commissioned officers from the Regular Army and wider Army Reserve.

The Infantry of the British Army comprises 49 infantry battalions, from 19 regiments. Of these, 33 battalions are part of the Regular army and the remaining 16 a part of the Army Reserve. The British Army's Infantry takes on a variety of roles, including armoured, mechanised, air assault and light.