What is Hamas? Group that rules Gaza Strip has fought several rounds of war with Israel

Hamas, which has ruled the Gaza Strip since 2007, launched an attack inside Israel over the weekend, killing hundreds and taking others hostage. Its unprecedented breach of the border sent fighters inside border communities and military installations, shocked Israel and its allies, and raised questions about the group’s capabilities and strategy.

The group was founded in 1987 by Sheikh Ahmed Yassin, a Palestinian refugee living in Gaza, during the first intifada, or uprising, which was marked by widespread protests against Israel’s occupation.

Hamas is the Arabic acronym for the Islamic Resistance Movement, and a recognition of the group’s roots and early ties to one of the Sunni world’s most prominent groups, the Muslim Brotherhood, founded in Egypt in the 1920s.

The group has vowed to fight Israel and has been responsible for many suicide bombings and other deadly attacks on civilians and Israeli soldiers. The US State Department has designated Hamas a terrorist group in 1997. The European Union and other Western countries also consider it a terrorist organisation.

Hamas won 2006 parliamentary elections elections and in 2007 violently seized control of the Gaza Strip from the internationally recognised Palestinian Authority. The Palestinian Authority, dominated by rival Fatah movement, administers semi-autonomous areas of the Israeli-occupied West Bank.

Israel responded to the Hamas takeover with a blockade on Gaza, restricting movement of people and goods in and out of the territory in a step it says is needed to keep the group from developing weapons. The blockade has ravaged Gaza's economy, and Palestinians accuse Israel of collective punishment.

Hamas founder and spiritual leader Yassin spent years in Israeli prisons and oversaw the establishment of Hamas' military wing, which carried out its first suicide attack in 1993.

Israeli forces have targeted Hamas leaders throughout the years, killing Yassin in 2004. Khaled Mashaal, an exiled Hamas member who survived an earlier Israeli assassination attempt, became the group’s leader soon after.

Yehia Sinwar, in Gaza, and Ismail Haniyeh, who lives in exile, are Hamas' current leaders. They realigned the group’s leadership with its allies, including Lebanon's Hezbollah. Since then, many of the group’s leaders relocated to Beirut.

Hamas has always espoused violence as a means to liberate occupied Palestinian territories and has called for Israel's destruction.

Hamas has carried out suicide bombings and over the years fired tens of thousands of increasingly powerful rockets from Gaza into Israel. It also established a network of tunnels running from Gaza to Egypt to smuggle in weapons, as well as attack tunnels burrowing into Israel.

• 'My heart dropped': Families fear for Thais held by Hamas