A reservist is a person who is a member of a reserve military force. They are otherwise civilians, and in peacetime have careers outside the military. Reservists usually go for training on an annual basis to refresh their skills. This person is usually a former active-duty member of the armed forces, and he remains a reservist either voluntarily, or by obligation. In some countries such as Israel, Singapore, Serbia and Switzerland, reservists are conscripted soldiers who are called up for training and service when necessary.
The Krümpersystem, introduced to the Prussian army by the military reformer Gerhard von Scharnhorst, arranged for giving recruits a short period of training, which in the event of war could be considerably expanded. With this the reduction of the army's strength did not have the desired effect, and in the following wars Prussia was able to draw up a large number of trained soldiers. By the time of the Second Reich reservists were already being given so-called 'war arrangements' following the completion of their military service, which contained exact instructions relating to the conduct of reservists in time of war.
Reservists are an integral part of the Bundeswehr. They are essential for the capability of the armed forces in time of war.
Reservists can be active in the Bundeswehr in addition to their mandatory service. This mostly happens through (mostly voluntarily) military exercises or official events. Apart from that the Bundeswehr organises reservist unions as particularly representative supporting organisations of "voluntarily reservist work".
Eligibility for compulsory military service for soldiers and other servicemen of low rank ends at the end of the 45th year of age. Thereafter the conscript is no longer part of the reserve. Despite that the appellations "a.D." and/or "d.R." may still be used. Conscription for under-officers and officers lasts until the 60th year of age. Until the 32nd year of age every conscript is subject to military inspection.
Recognised conscientious objectors, who have competed their civil service, are nonetheless part of the reserve and in the event of war will be given a suitable non-combatant role outside the Bundeswehr, such as emergency medical services, clearing debris or minesweeping.
All conscripts who have not done their service belong to the Ersatzreserve (replacement reserve).
When a conscript completes his full time service, he is considered to be "operationally ready", and is thereafter known as an Operationally-Ready National Serviceman (NSman). NSmen are the equivalent of other militaries' reservists. The difference in nomenclature is because these NSmen will form the bulk of the Singapore Armed Forces in times of war. The term Operationally-Ready National Servicemen conveys more importance than the reservists. Similarly, Operationally-Ready NSmen of the SPF and SCDF are available to be called on in time of need.
NSmen are liable for 10 NS training cycles of up to 40 days a year, not necessarily consecutively. After that, they are called up for training for up to 3 days a year until the age of 40 or 50, depending on their rank. After which, they will then be assigned to be military reserves (MR). However, any servicemen may opt not to go MR by volunteering their services as NSmen for a longer period of time.
There is also the United States National Guard, which is under dual Federal/State control, and is traditionally intended for homeland defense and domestic disaster relief (although large numbers are currently deployed in Iraq, and as such the distinction between National Guardsmen and Reservists has become blurred). The National Guard is divided into:
During peacetime Reservists and National Guardsmen spend one weekend a month, two weeks a year annually in training.