Four years after the last major conflict in the region, Israel and Hamas have once again been on the brink of war in Gaza, though an Egypt-brokered cease-fire appears to be holding, paving the way for peace talks in future. So what is the group, and what does it hope to achieve by its rocket attacks on Israeli targets?
What is Hamas?
Hamas is a militant fundamentalist Islamic organization operating in the West Bank and Gaza. The name Hamas is an acronym for "Harakat Al-Muqawama Al-Islamia," or Islamic Resistance Movement in English. The word "hamas" means zeal, or enthusiasm, in Arabic.
Hamas has sections dedicated to religious, military, political and security activities. It runs a social welfare program, and operates a number of schools, hospitals and religious institutions.
What are its aims?
The goal of Hamas is an Islamic fundamentalist Palestinian state. Its manifesto advocates the destruction of the state of Israel, and calls for the raising of "the banner of Allah over every inch of Palestine."
Hamas members, like most Palestinian factions and political parties, insist that Israel is an occupying power, and that the group is simply trying to liberate the Palestinian territories.
"The Palestinian people were living in peace and security, then the Israelis occupied the land," Khaled Meshaal, the political leader of Hamas, told CNN. "According to international law, and according to the Divine laws, the Americans and all peoples, when they are occupied, they resist with all that they have."
When an Israeli airstrike killed the group's military leader, Ahmed Ja'abari, this month, Hamas warned Israel that it had "opened the gates of hell on itself."
Meshaal has previously said the group would support a Palestinian state based on the borders that existed prior to the 1967 Six-Day War, during which Israeli troops occupied Gaza, the West Bank, the Golan Heights and East Jerusalem, with East Jerusalem as its capital. However, he has stopped short of backing a full two-state solution, including acceptance of Israel's right to exist.
The refusal of Hamas to recognize the state of Israel is one reason why it has rejected peace talks in the past. In 1993, it opposed the Oslo Accords, a peace pact between Israel and the Palestine Liberation Organization (PLO).
Speaking following the most recent outbreak of violence, Mark Regev, spokesman for Israeli Prime Minister Benjamin Netanyahu, said: "Hamas is an enemy of peace. [It] is dedicated to destroying the state of Israel."
But Robert Blecher, Israel and Palestine Program Director at the International Crisis Group, said claims that Hamas wanted to see Israel "wiped off the map" were outdated.
"The document still exists as their official charter, but many people in Hamas view it is a historical document, an artifact, rather than as an active program" since Hamas has agreed to other commitments that go against it in more recent years.
Even so, it is unlikely to be altered any time soon. "It can't be changed under the current political conditions, because if they gave in to the demands of others to change it, it would look like they were making a concession," Blecher told CNN.
What are Hamas' origins?
Hamas was established in 1987 -- during the First Intifada, or uprising -- by Sheikh Ahmed Yassin.
Yassin and other activists linked to Egypt's Muslim Brotherhood movement had set up a network of charities, schools and clinics in the West Bank and Gaza in the 1960s, '70s and '80s. Initially, their activities were encouraged by some Israeli politicians, who saw the group as an alternative to the PLO and a way of lessening the influence of its leader, Yasser Arafat.
However, the founding charter of Hamas, published in 1988, called for jihad, or holy war, against Israel.
The following year, Yassin -- a partially blind quadriplegic -- was convicted by an Israeli court of ordering Hamas members to kidnap and kill two Israeli soldiers. He was released from jail in 1997 as part of a prisoner exchange, traded for two Israeli agents captured in Jordan during an attempt to assassinate Khaled Meshaal. Yassin was killed in an Israeli airstrike in 2004, after surviving an earlier attempt on his life the previous year.
The group began carrying out suicide bombings on civilian and military Israeli targets in the mid 1990s. According to the Council on Foreign Relations, Hamas is believed to have killed more than 500 people in more than 350 separate terrorist attacks since 1993.
What are the Izzedine al Qassam Brigades?
The Izzedine al Qassam Brigades are the armed wing of Hamas, responsible for carrying out attacks on Israel. Like the wider Hamas organization, the aim of the Brigades is the creation of a Palestinian state.
Beginning in the mid-1990s, the Brigades began a campaign of attacks against military targets and civilians that included suicide bombings, car bombings, and rocket attacks in Israel, as well as attacks on Israeli settlers in the West Bank, before Israel's pullout, in Gaza.
However, since Hamas took over Gaza in 2007, the Brigades have "transformed from an underground guerrilla organization into a uniformed military force designed to protect Gaza from outside attack," according to the International Crisis Group.