Is peace possible? Israel awoke to a bloody incursion on Saturday morning during a Jewish holiday, and promptly declared war. Amid deep civilian losses on both sides, some wonder if peace will ever come to pass.
World on high alert after Israel declares war
Boiling point: Buildings go up in smoke in Gaza as Israel vows "mighty vengeance" on Hamas. Glossary
Sukkot - A Jewish autumn festival of thanksgiving, celebrated for seven days.
Simchat Torah - A Jewish religious holiday in early October, celebrating the completion of the annual reading of the Torah.
Torah - The five books of the Hebrew Bible. It is Judaism's most important document.
Incursion - Sudden or brief invasion.
Palestinian - Palestine is an area of the eastern Mediterranean region, including the West Bank, Gaza Strip and parts of modern Israel. It has been fought over by Arab and Jewish national movements for many years.
Hamas - A militant Palestinian organisation, which has controlled the Gaza Strip since 2007. It is listed as a terrorist organisation in the UK.
Gaza - The smaller of two Palestinian territories, home to two million people. It is located on the Mediterranean coast, bordered by Israel and Egypt.
Barrage - A bombardment of multiple artillery weapons over a large area.
Retaliatory - In response to previous attacks.
Immeasurable - Not able to be measured or counted.
Nagorno-Karabakh - A mountainous region of the South Caucasus. The area is disputed by Azerbaijan and Armenia.
Kosovo - A landlocked country in the Balkans in southeast Europe. It has a population of 1.87 million.
Repercussions - The effects, usually bad, of an event or action.