I want to be clear- I don't think I really understood what present-day Settlements were before I got here. People told me, but I don't think I really got it. So I will take a go at saying some of what I've learned. In 1967, the Israeli Military occupied the West Bank, an area of Palestine which between 1948 and 1967 was largely controlled by Palestinians. Since 1967, the Military controls much of life in the West Bank and though the entire occupation is against International Law, the Israeli Military basically does whatever they want to whenever they want to to Palestinians here.
Settlements are a project of the Israeli State to take over more and more land away from Palestinians in the Occupied territories (West Bank and Gaza)- effectively making it near to impossible for Palestinians to live and work here, and seeing it with my own eyes- there is a clear goal of getting Palestinians to leave here and never come back. But still they remain!
The vast majority of Settlers are here for economic reasons- a ton of tax subsidies, etc. Their presence is violent - they live on land where until recently, Palestinians lived, harvested almonds, olives, etc. Settlement sewage and garbage is often dumped in what remains of neighboring village, etc. I've seen this with my own eyes. Settler/Israeli-only roads have been built and designated- which are closed to Palestinians, sometimes even when it's the only road that connects their villages to the rest of the West Bank.
And then, some Settlers are in the West Bank for ideological reasons, and these Settlers make life for Palestinians intensely dangerous on a day to day bases (which I will write about in future posts).