Israel/Palestine was the ancestral home of the Hebrew (ie. Jewish) people, up until about 700AD.
From then, right up until 1948, it was held by the Arab people in the region, the people now known as Palestinians.
At the end of World War II, there were hundreds of thousands of displaced Jewish refugees all over Europe and the rest of the world - and no country really wanted to take them.
So the United Nations put some weight behind a rather niche interest group (the Zionists) who wanted to reclaim Palestine for the Jewish people, 1200 years after they left.
Palestine wasn’t OK with losing a major chunk of its land with no recompense, but the UN said tough shit sucks to be you lol, and gave them no choice, establishing the modern country of Israel within its borders, kicking out the Palestinians who had been living there for the past 1200 years and settling vast numbers of refugees in a ready-made country.
This held a certain amount of strategic value to the West, as a political, economic and military power base smack bang in the middle of the Middle East, standing opposed to the Arab nations surrounding it, and giving the west a foot in the door and a finger in all the pies, as it were.
As a result, Israel has had virtually unlimited economic and military aid from the west ever since, and become comfortably rich despite having no exports, resources or trade to speak of.
Since 1948, Palestine has made various efforts to reclaim some of its land - and each time, has been beaten back by the combined military might of the entire west, losing ever more territory with each attempt.
Israel now holds virtually all of Palestine, except for tiny fractured and scattered pockets of land - which they keep ‘settling’ - eg. annexing and invading, killing the Palestintian inhabitants, demolishing their homes, burning their farms and taking their land. Palestinians are allowed into Israel, but as second-class citizens in an apartheid regime, exploited for cheap labour.
Palestine no longer has the resources, organization, wealth or strength to maintain an actual military or to mount actual resistance - with guerilla warfare being the only tactic available. And of course where you have poverty and oppression, that’s fertile ground for radicalisation - and this has lead to exploitation by various terrorist groups.
Now, Gaza is a small contiguous chunk of Palestine, bordering on Egypt - and Israel has been blockading it for decades, severely limiting access to food, water, building materials, etc - basically a giant open-air prison camp, with severe reprisals (such as bombing schools and hospitals - collective punishment, which is a war crime) for any attacks on Israel.
It’s this region that’s been the source of the latest conflict - with Hamas (a very unpleasant bunch of people) launching a major offensive, consisting of both rocket strikes and armed incursions, targeting Israeli civilians.
There’s every indication that this was planned and supported by Iran, who have their own agenda, and are happy to see Palestinians and Israelis both get killed.
Israel has responded to the attacks by bombing Gaza quite indiscriminately, and shutting off power, water and food supplies entirely to all of Gaza.
Israel is continuing to act the victim/hero for its actions, as always, and is receiving a vast outpouring of western aid, support and political clout in return.
To complicate matters, half of the religious right in the US is fervently pro-Israel, because despite disapproving of Judaism for rejecting Jesus, they believe that biblical prophesy is predicated on Jewish control of Israel. Yes, seriously. They can’t have their Armageddon and be carried up to heaven unless the events in Revelations come to pass, and yeah.
Also, ever since WWII, Israel has been playing the fuck out of the antisemitism card, loudly declaring that any opposition to their policy and actions must be rooted in hatred of Jewish people, and is obviously just softening up the ground for neo-nazis. And of course, no politician wants to get tarred with that brush.