The mission has been running for more than four years, beginning in September 2014 over Iraq when the Royal Air Force flew its first combat sorties of the operation.
Air strikes over Syria were first launched December 2015, following approval from the British Government.
The UK is the second largest contributor behind the US, with jets flying missions from RAF Akrotiri in Cyprus.
Since Op Shader began, the RAF has conducted more than a thousand air strikes over Iraq and Syria, using more than 4,300 weapons launched from Tornado, Typhoon and Reaper aircraft.
The RAF carried out its 1,000th air strike against IS, also known as Daesh, in September 2017.
History of Operation Shader
The British operation against so-called Islamic State began in Iraq on 26 September 2014 following a formal request for assistance by the Iraqi government.
In October 2014, the UK operation extended also to Syria, where the Royal Air Force conducted several surveillance flights. MQ-9 Reaper drones based in Cyprus were responsible for 30% of aerial surveillance over Syria.
Tornado jets have been involved since the beginning of the mission. Typhoon aircraft joined the operation in late 2015, when Parliament voted to extend the air campaign against Daesh to Syria.
In September 2017, the RAF carried out their 1000th air strike against Daesh targets.
At the same time, then-Defence Secretary Sir Michael Fallon announced an Iraq and Syria Operational Service Medal as part of his visit to Iraq on the eve of Operation Shader’s three-year anniversary.
Currently, tri-service personnel are manning roles with the Global Coalition's headquarters throughout the Middle-East, including in Baghdad where there are UK advisors working alongside Iraqi military personnel in the Iraqi Operational Command.
Earlier this year, the Defence Secretary confirmed that IS has not been completely defeated, and that there is an "ongoing threat" from the militants, but that all areas once occupied by Daesh in Iraq and Syria have been liberated.