Islamic Jihad may be one of the best known names associated with Palestinian militancy, but it has always been a relatively small and shadowy organisation.
Islamic Jihad is one of the most hardline Palestinian groups
The group - made up of a handful of loosely affiliated factions divided up into cells - has traditionally concentrated on attacking Israel, eschewing the prominent social, welfare and political role taken on by other Islamist groups like Hamas or the Lebanon's Hezbollah.
This is a reflection of Jihad's ideological stance which holds that the Arab-Israeli conflict will only be resolved through armed confrontation.
Israel is considered - along with pro-Western, secular Arab regimes - as a manifestation of Western imperialism in the Islamic lands; going into battle against it is therefore the first step to fulfilling the goals of Islam.
Jihad has claimed responsibility for dozens of attacks since the outbreak of the intifada in September 2000, ranging from armed infiltrations of Jewish settlements and ambushes to car bombs and suicide bombings on Israeli buses.
But Jihad cells have also resorted to less "conventional" terrorist tactics, such as the stoning to death of two 14-year-old boys abducted from a West Bank settlement in May 2001.
Jihad has claimed responsibility for dozens of intifada attacks
The most devastating intifada operations have been a car bomb attack against an Israeli bus in June 2002, killing 17 people, and the ambush in Hebron against settlers and Israeli troops on 15 November that left 14 Israelis dead.
In all more than 60 Israeli lives have been lost in Jihad attacks during the intifada, with about 40 suicide attackers dying in the process.
The group, also known as PIJ in the West, was founded by three Palestinian students studying in Egypt in the late 1970s - Fathi Shikaki, Abdul Aziz Odeh and Bashir Moussa.
Although Sunni Muslims, they were inspired by the Islamic revolution which installed a Shia theocracy in power in Iran.
Booted out of Egypt to Gaza after the assassination of President Sadat by Egyptian Islamist soldiers, the leadership of PIJ began organising in the Israeli-occupied territories and elsewhere in the early 1980s.
Successful Jihad attacks have won the organisation popular support
Their first successful strike is thought to have been in Gaza, the killing of an Israeli military police captain in August 1987, a few months before the first Palestinian intifada.
The following year Shikaki and Odeh were expelled again, this time by the Israeli authorities, to Lebanon - but that did not prevent PIJ from launching a series of bomb and other attacks against Israeli military and civilian targets.
The group has had a mixed history of relations with Palestinian leader Yasser Arafat's Fatah movement. A shared liberation ideology brought them together in an earlier period of the Palestinian revolution - until Mr Arafat renounced the armed struggle against Israel in the late 1980s.
PIJ subsequently did its best to blow Arafat's Oslo peace process off course - conducting some devastating attacks such as the bombing of a military bus stop near Netanya in January 1995 and a suicide nail bomb in Tel Aviv in March 1996.
Attacks like this, which killed 19 and 13 Israelis respectively, increased the determination of Israel's then-Labour government to pursue peace.
Hamas leader Shallah (right) lives in exile in Syria
The attacks also went a long way towards shaking public confidence in Israel, which saw the election of a right-wing government in May 1996 that presided over deadlock in negotiations that the peace process never recovered from.
But back in October 1995, while Labor was talking peace with Mr Arafat, Israel's security forces were fighting a ruthless anti-terror campaign, during which Fathi Shikaki was gunned down in Malta by unknown assassins - thought to be working for the Israeli intelligence service Mossad.
Leadership of the organisation passed to Ramadan Abdullah al-Shallah, whose academic links in the West (he has a doctorate from the University of Durham and had just left a post at the University of South Florida) caused some controversy.
Its string of successful attacks have brought PIJ new support from Palestinians angry over harsh Israeli security measures and Israel's perceived intransigence towards a return to peace talks.
It has also grown increasingly close to Hamas, as the two groups' methods and long-term goals have converged.
Ordinary Palestinians have also come out on to the streets to celebrate Jihad violence visited on Israel, while what is left of the Palestinian Authority has singularly failed to clamp down on the group.