Squadrons are the main form of flying unit of the Royal Air Force (RAF). These include Royal Flying Corps (RFC) and Royal Naval Air Service (RNAS) squadrons incorporated into the RAF when it was formed on 1 April 1918, during the First World War. Other squadrons of the RAF include those from Commonwealth air forces which have served within the RAF structure and squadrons of the Fleet Air Arm before it transferred to the Royal Navy in 1939.
Some squadrons have an individual tradition of presenting their squadron number in Roman numerals or using a suffix to their squadron number (such as "(F)" for "Fighter", "(B)" for "Bomber" or "(AC)" for "Army Co-operation") to indicate a past or present role. An example would be No. 18 (Bomber) Squadron RAF which currently actually operates the heavy-lift Chinook helicopter. However, these practices have, at least in the past, been deprecated at higher levels and generally only apply to certain squadrons with long traditions, especially those numbered from 1 to 20.[1] Historical Squadrons can choose to 'lay up' their standards at RAF Cranwell or in places of worship following disbandment.
Flying training units and operational evaluation squadrons have generally been (Reserve) squadrons, although they are regular active-duty units. The policy of the (Reserve) numberplate was rescinded in February 2018, to coincide with the renaming of 22 (Training) Group to just 22 Group in line with other RAF Groups.
Some Squadron names include the location they were originally formed.