What is Islamic Jihad, the group being blamed by Israel for bombing at Gaza hospital?

An explosion at a Gaza hospital sparked outrage and protests, with blame exchanged between Israel and Palestinians. Islamic Jihad, a Palestinian militant group formed in 1981, has been implicated in the incident. Islamic Jihad opposes the peace process with Israel and seeks to establish an Islamic state in Palestine. The group operates mainly in Gaza and has carried out attacks on Israeli targets. It is allied with Hamas and receives support from Iran and Syria.