An order from Defense Minister David Ben-Gurion on 26 May 1948 officially set up the Israel Defense Forces as a conscript army formed out of the paramilitary group Haganah, incorporating the militant groups Irgun and Lehi. The IDF served as Israel's armed forces in all the country's major military operations—including the 1948 War of Independence, 1951–1956 Retribution operations, 1956 Sinai War, 1964–1967 War over Water, 1967 Six-Day War, 1967–1970 War of Attrition, 1968 Battle of Karameh, 1973 Operation Spring of Youth, 1973 Yom Kippur War, 1976 Operation Entebbe, 1978 Operation Litani, 1982 Lebanon War, 1982–2000 South Lebanon conflict, 1987–1993 First Intifada, 2000–2005 Second Intifada, 2002 Operation Defensive Shield, 2006 Lebanon War, 2008–2009 Operation Cast Lead, 2012 Operation Pillar of Defense, and 2014 Operation Protective Edge. The number of wars and border conflicts in which the IDF has been involved in its short history makes it one of the most battle-trained armed forces in the world. While originally the IDF operated on three fronts—against Lebanon and Syria in the north, Jordan and Iraq in the east, and Egypt in the south—after the 1979 Egyptian–Israeli Peace Treaty, it has concentrated its activities in southern Lebanon and the Palestinian Territories, including the First and the Second Intifada.
The Israel Defense Forces differs from most armed forces in the world in many ways. Differences include the mandatory conscription of women and its structure, which emphasizes close relations between the army, navy, and air force. Since its founding, the IDF has been specifically designed to match Israel's unique security situation. The IDF is one of Israeli society's most prominent institutions, influencing the country's economy, culture and political scene. In 1965, the Israel Defense Forces was awarded the Israel Prize for its contribution to education. The IDF uses several technologies developed in Israel, many of them made specifically to match the IDF's needs, such as the Merkava main battle tank, Achzarit armoured personnel carrier, high tech weapons systems, the Iron Dome missile defense system, Trophy active protection system for vehicles, and the Galil and Tavor assault rifles. The Uzi submachine gun was invented in Israel and used by the IDF until December 2003, ending a service that began in 1954. Since 1967, the IDF has had close military relations with the United States, including development cooperation, such as on the F-15I jet, THEL laser defense system, and the Arrow missile defense system.
The Israel Defense Forces are believed to have had an operational nuclear weapons capability since 1967, possibly possessing between 80 and 400 nuclear weapons, with delivery systems forming a nuclear triad, of plane launched-missiles, Jericho III intercontinental ballistic missiles and submarine launched cruise missiles.
The Israeli cabinet ratified the name "Israel Defense Forces" (Hebrew: צְבָא הַהֲגָנָה לְיִשְׂרָאֵל), Tzva HaHagana LeYisra'el, literally "army for the defense of Israel," on 26 May 1948. The other main contender was Tzva Yisra'el (Hebrew: צְבָא יִשְׂרָאֵל). The name was chosen because it conveyed the idea that the army's role was defense, and because it incorporated the name Haganah, the pre-state defensive organization upon which the new army was based. Among the primary opponents of the name were Minister Haim-Moshe Shapira and the Hatzohar party, both in favor of Tzva Yisra'el.
The IDF traces its roots to Jewish paramilitary organizations in the New Yishuv, starting with the Second Aliyah (1904 to 1914). The first such organization was Bar-Giora, founded in September 1907. Bar-Giora was transformed into Hashomer in April 1909, which operated until the British Mandate of Palestine came into being in 1920. Hashomer was an elitist organization with narrow scope, and was mainly created to protect against criminal gangs seeking to steal property. The Zion Mule Corps and the Jewish Legion, both part of the British Army of World War I, would further bolster the Yishuv with military experience and manpower, forming the basis for later paramilitary forces. After the 1920 Palestine riots against Jews in April 1920, the Yishuv leadership realised the need for a nationwide underground defense organization, and the Haganah was founded in June of the same year. The Haganah became a full-scale defense force after the 1936–1939 Arab revolt in Palestine with an organized structure, consisting of three main units—the Field Corps, Guard Corps, and the Palmach. During World War II, the Yishuv participated in the British war effort, culminating in the formation of the Jewish Brigade. These would eventually form the backbone of the Israel Defense Forces, and provide it with its initial manpower and doctrine.