Here is a discription taken from B'Tselem's website:
In June 2002, the government of Israel decided to erect a physical barrier to separate Israel and the West Bank in order to prevent the uncontrolled entry of Palestinians into Israel . In most areas, the barrier is comprised of an electronic fence with dirt paths, barbed-wire fences, and trenches on both sides, at an average width of 60 meters. In some areas, a wall six to eight meters high has been erected in place of the barrier system.This wall does not run along the border of Israel, but actually runs through the West Bank, separating families and villages. There are nearly 30,000 Palestinians living on the west side of the barrier, Palestinians who will now require permits to live in their homes which are in the West Bank, and will be completely cut off from the rest of their people. These statistics do not include East Jerusalem, where nearly a quarter of a million Palestinians live.
In July of 2004 the International Court of Justice condemened the wall as being illegal, and a major abuse of human rights:
In its conclusion, the court stated that Israel must cease construction of the barrier, dismantle the parts of the barrier that were built inside the West Bank, revoke the orders issued relating to its construction, and compensate the Palestinians who suffered losses as a result of the barrier. The court also called on the international community to refrain from assisting in maintaining the unlawful situation that has arisen following construction of the barrier, and to take legal measures to cease Israel's violations and to ensure enforcement of the Fourth Geneva Convention.Israel did not deny the charges. Instead, it simply claimed that human rights were irrelevant when dealing with the Palestinian people. It has ignored the court's ruling.