Profile: Hamas Palestinian movement
Hamas is the largest of several Palestinian militant Islamist groups and governs the Gaza Strip.
Its name is an Arabic acronym for the Islamic Resistance Movement, originating as it did in 1987 after the beginning of the first intifada, or Palestinian uprising, against Israel's occupation of the West Bank and Gaza.
Prior to its role as a government, Hamas's purpose was armed struggle (led by its military wing, the Izz al-Din Qassam Brigades) against Israel, and delivering social welfare programmes.
Hamas is designated a terrorist organisation by Israel, the US and EU, due to its long record of attacks and its refusal to renounce violence. Under the group's charter, Hamas is committed to the destruction of Israel.
But to its supporters it is seen as a legitimate resistance movement and a democratically elected government.
In 2006, it won a stunning victory in the Palestinian parliamentary elections, sparking a bitter conflict with the rival Fatah faction of Palestinian leader Mahmoud Abbas.
Tensions spilled over into deadly clashes between rival militants on the streets of Gaza in June 2007. Since then, the two factions have remained politically and geographically divided for more than four years, with Hamas in power in Gaza and Fatah running parts of the West Bank.
Finally, in May 2011, they signed a reconciliation pact in Cairo, but it has not yet yielded a breakthrough on a Palestinian government of national unity.
In October 2011, Hamas boosted its popularity when it secured the release of more than 1,027 Palestinians held in Israeli prisons in exchange for Israeli soldier Gilad Shalit, captured by militants during a cross-border raid in June 2006.
Israel holds Hamas responsible for all attacks emanating from the Gaza Strip, and has carried out two major military campaigns in Gaza since Hamas came to power - Operation Cast Lead in December 2008 and Operation Pillar of Defence in November 2012.
The offensives were preceded by escalations in cross-border fighting, with scores of rocket attacks from Gaza, and air strikes against it by Israel.
Hamas emerged from both conflicts militarily degraded but with renewed support among Palestinians in Gaza and the West Bank for having confronted Israel and survived.Origins
Hamas came to prominence after the first intifada as the main Palestinian opponent of the Oslo accords - the US-sponsored peace process that oversaw the gradual and partial removal of Israel's occupation in return for Palestinian guarantees to protect Israeli security.
Despite numerous Israeli operations against it and clampdowns by the Palestinian Authority, Hamas found it had an effective power of veto over the process by launching suicide attacks.
In February and March 1996, it carried out several suicide bus bombings, killing nearly 60 Israelis, in retaliation for the assassination in December 1995 of Hamas bomb maker Yahya Ayyash.
The bombings were widely blamed for turning Israelis off the peace process and bringing Benjamin Netanyahu - a staunch opponent of the Oslo accords - to power.
In the post-Oslo world, most particularly following the failure of US President Bill Clinton's Camp David summit in the summer of 2000 and the second intifada which followed shortly thereafter, Hamas gained power and influence as Israel steadily destroyed the infrastructure of the Palestinian Authority, which it accused of sponsoring deadly attacks.
Hamas organised clinics and schools which served Palestinians who felt let down by the corrupt and inefficient PA, dominated by Fatah.
Many Palestinians cheered the wave of Hamas suicide attacks in the first years of the intifada.
They saw "martyrdom" operations as the best way to avenge their own losses and counter Israel's unchecked settlement building in the West Bank.
After the death of Fatah leader Yasser Arafat in 2004, the Palestinian Authority was taken over by Mahmoud Abbas, a vocal opponent of attacks on Israel.
He viewed Hamas rocket fire as counter-productive, inflicting little damage on Israel but provoking a harsh response by the Israeli military.
When Hamas scored a landslide victory in 2006, the stage was set for a bitter power struggle with Fatah.
Hamas resisted all efforts to get it to sign up to previous agreements with Israel, as well as to recognise Israel's legitimacy and to give up the armed struggle.
Hamas's charter defines historic Palestine - including present-day Israel - as Islamic land and it rules out any permanent peace with the Jewish state.
The charter also repeatedly makes attacks on Jews as a people, drawing charges that the movement is anti-Semitic.
Hamas has, however, offered a 10-year truce in return for a complete Israeli withdrawal from territories occupied in 1967: the West Bank, Gaza Strip and East Jerusalem.
It insists though that millions of Palestinian refugees stemming from the 1948 war must be allowed to return to homes in what became Israel - a move that would threaten Israel's very existence.
Over the years Hamas has lost many members in Israeli assassinations and security sweeps.
- Sheikh Yassin was killed in a missile attack on 22 March 2004
- Abdul Aziz al-Rantissi emerged as Hamas leader in Gaza before he too was assassinated six weeks later on 17 April
- Other prominent Hamas officials killed by the Israelis include Qassam Brigades leader Salah Shehada in July 2002; Ismail Abu Shanab in August 2003 and Said Siyam in the Gaza Strip in January 2009
After the death of Sheikh Yassin, Khaled Meshaal became the group's political leader in exile.
However, he said in January 2012 he would not stand again, and the future make-up of Hamas's leadership remains to be determined, amid tensions between hardliners and those who favour a more pragmatic approach to both Israel and reconciliation with Fatah.Ballot box
Hamas's decision to stand in elections in 2006 was a major departure for the movement.
The new government was subjected to tough economic and diplomatic sanctions by Israel and its allies in the West.
Skirmishes in Gaza with the Fatah-dominated PA security forces escalated to all-out war, in which Hamas's well-armed and better-disciplined Qassam Brigades eventually ousted their rivals in June 2007.
Hamas security control made the Gaza Strip a more calm and orderly place than it had been for months, but the movement and its security apparatus has also been accused of major human rights abuses.
After Hamas came to power in Gaza, Israel tightened its blockade on the territory and rocket fire and Israeli raids continued to provide provocations for more violence by each side.
In December that year, Israel launched Operation Cast Lead - a 22-day offensive aimed, Israel said, at halting rocket attacks from Gaza. More than 1,300 Palestinians and 13 Israelis were killed.
Israel cited the same reason for another operation in November 2012 - Pillar of Defence - which began with an air strike that killed Ahmed Jabari, the Qassam Brigades commander. Some 170 Palestinians - mostly civilians - and six Israelis died in the eight-day conflict.