Who was Yahya Sinwar?

Israel’s Prime Minister has called Yahya Sinwar’s death an opportunity for the people of Gaza to free themselves from the tyranny of Hamas – and US President Joe Biden echoed this.

He has just called it “a good day for Israel, the United States and the world”.

And he added that now is the opportunity for a “day after” in Gaza, without Hamas in power.

But who exactly was Yahya Sinwar?