A ceasefire (or truce), also spelled cease fire (the antonym of 'open fire'), is a temporary stoppage of a war in which each side agrees with the other to suspend aggressive actions. Historically, the concept existed at least by the time of the Middle Ages, when it was known as a 'truce of God'. Ceasefires can be declared as a humanitarian gesture, be preliminary, i.e., prior to a political agreement, or definitive, i.e., with the intention of resolving a conflict. Ceasefires may be declared as part of a formal treaty, but they have also been called as part of an informal understanding between opposing forces.
Ceasefires may be between state actors or involve non-state actors. They may be formal (usually written), or informal; their conditions may be public or secret. Ceasefires may occur via mediation or otherwise as part of a peace process or be imposed by United Nations Security Council resolutions via Chapter VII of the United Nations Charter.
A ceasefire is usually more limited than a broader armistice, which is a formal agreement to end fighting. Ceasefires may be abused by parties as cover to re-arm or reposition forces, and they typically fail, when they are referred to as 'failed ceasefires'; however, successful ceasefires may be followed by armistices and then by peace treaties.
The durability of ceasefire agreements is affected by several factors, such as demilitarized zones, withdrawal of troops and third-party guarantees and monitoring (e.g. peacekeeping). Ceasefire agreements are more likely to be durable when they reduce incentives to attack, reduce uncertainty about the adversary's intentions, and when mechanisms are put in place to prevent and control accidents from developing into conflict.
Main article: Christmas truce
During World War I, on December 24, 1914, there was an official ceasefire on the Western Front as France, the United Kingdom, and Germany observed Christmas. There are accounts that claimed the unofficial ceasefire took place throughout the week leading to Christmas, and that British and German troops exchanged seasonal greetings and songs between their trenches. The ceasefire was brief but spontaneous. Beginning when German soldiers lit Christmas trees, it quickly spread up and down the Western Front. One account described the development in the following words:
It was good to see the human spirit prevailed amongst all sides at the front, the sharing and fraternity. All was well until the higher echelons of command got to hear about the effect of the ceasefire, whereby their wrath ensured a return to hostilities.
There was no peace treaty signed during the Christmas truce, and the war resumed after a few days.
Main article: Karachi Agreement
The Karachi Agreement of 1949 was signed by the military representatives of India and Pakistan, supervised by the United Nations Commission for India and Pakistan, establishing a cease-fire line in Kashmir following the Indo-Pakistani War of 1947.
On November 29, 1952, the US president-elect, Dwight D. Eisenhower, went to Korea to see how to end the Korean War. With the UN's acceptance of India's proposed armistice, the ceasefire of the Korean People's Army (KPA), the People's Volunteer Army (PVA), and the UN Command had the battle line approximately at the 38th parallel north. These parties signed the Korean Armistice Agreement on July 27, 1953, to end the fighting. South Korean President Syngman Rhee attacked the peace proceedings and did not sign the armistice. Upon agreeing to the ceasefire agreement, which called upon the governments of South Korea, North Korea, China, and the United States to participate in continued peace talks. The principal belligerents established the Korean Demilitarized Zone (DMZ), which has since been patrolled by the KPA and the joint Republic of Korea Army, US, and UN Command. The war is considered to have ended at that point even though there still is no peace treaty.
On New Years Day, 1968, Pope Paul VI convinced South Vietnam and the United States to declare a 24-hour-truce. However, the Viet Cong and North Vietnam did not adhere to the truce, and ambushed the 2nd Battalion, Republic of Vietnam Marine Division, 10 minutes after midnight in Mỹ Tho. The Viet Cong would also attack a U.S. Army fire support base near Saigon, causing more casualties.
On January 15, 1973, US President Richard Nixon ordered a ceasefire of the aerial bombings in North Vietnam. The decision came after Henry Kissinger, the National Security Advisor to the President, returned to Washington, DC, from Paris, France, with a draft peace proposal. Combat missions continued in South Vietnam. By January 27, 1973, all parties of the Vietnam War signed a ceasefire as a prelude to the Paris Peace Accord.
After Iraq was driven out of Kuwait by US-led coalition forces during Operation Desert Storm, Iraq and the UN Security Council signed a ceasefire agreement on March 3, 1991. Subsequently, throughout the 1990s, the U.N. Security Council passed numerous resolutions calling for Iraq to disarm its weapons of mass destruction unconditionally and immediately. Because no peace treaty was signed after the Gulf War, the war still remained in effect, including an alleged assassination attempt of former US President George H. W. Bush by Iraqi agents while on a visit to Kuwait; Iraq being bombed in June 1993 as a response, Iraqi forces firing on coalition aircraft patrolling the Iraqi no-fly zones, US President Bill Clinton's bombing of Baghdad in 1998 during Operation Desert Fox, and an earlier 1996 bombing of Iraq by the US during Operation Desert Strike. The war remained in effect until 2003, when US and UK forces invaded Iraq and toppled Saddam Hussein's regime from power.
A UN-mediated ceasefire was agreed between India and Pakistan, on 1 January 1949, ending the Indo-Pakistani War of 1947 (also called the 1947 Kashmir War). Fighting broke out between the two newly independent countries in Kashmir in October 1947, with India intervening on behalf of the princely ruler of Kashmir, who had joined India, and Pakistan supporting the rebels. The fighting was limited to Kashmir, but, apprehensive that it might develop into a full-scale international war, India referred the matter to the UN Security Council under Article 35 of the UN Charter, which addresses situations "likely to endanger the maintenance of international peace". The Security Council set up the dedicated United Nations Commission for India and Pakistan, which mediated for an entire year as the fighting continued. After several UN resolutions outlining a procedure for resolving the dispute via a plebiscite, a ceasefire agreement was reached between the countries towards the end of December 1948, which came into effect in the New Year. The Security Council set up the United Nations Military Observer Group for India and Pakistan (UNMOGIP) to monitor the ceasefire line. India declared a ceasefire in Kashmir Valley during Ramadan in 2018.
The Irish Republican Army held several Christmas ceasefires (usually referred to as truces) during the Northern Ireland conflict. 
An example of a ceasefire in the Israeli–Palestinian conflict was announced between Israel and the Palestinian National Authority on February 8, 2005. When announced, chief Palestinian negotiator Saeb Erekat publicly defined the ceasefire as follows: "We have agreed that today President Mahmoud Abbas will declare a full cessation of violence against Israelis anywhere and Prime Minister Ariel Sharon will declare a full cessation of violence and military activities against Palestinians anywhere."
Main article: Syrian peace process
Several attempts have been made to broker ceasefires in the Syrian Civil War.
Main article: Global ceasefire
The 2020 global ceasefire was a response to a formal appeal by United Nations Secretary-General António Manuel de Oliveira Guterres on March 23 for a global ceasefire as part of the United Nations' response to the COVID-19 coronavirus pandemic. On 24 June, 2020, 170 UN Member States and Observers signed a non-binding statement in support of the appeal, rising to 172 on 25 June, 2020, and on 1 July 2020, the UN Security Council passed a resolution demanding a general and immediate global cessation of hostilities for at least 90 days.