Hamas and Fatah agree to form a government. What does it mean and who are these Palestinian groups?

Associated Press

RAMALLAH, West Bank (AP) — Palestinian factions and bitter foes Hamas and Fatah have signed a declaration in China vowing to form a unity government that would rule over the occupied West Bank and Gaza when the Israel-Hamas war ends. The agreement reached Tuesday in Beijing could mark the beginning of a reconciliation between the two heavyweights of Palestinian politics. Israel has ruled out any initiative that would lead to Hamas or the Fatah-dominated Palestinian Authority governing Gaza, and the deal appears to offer only the broadest outlines on how the two would work together.