As shown on this map from ReliefWeb, a service of the United Nations Office for the Coordination of Humanitarian Affairs (OCHA), due to the hostilities between Israel and Hamas, the liveable size of the Gaza has decreased substantially:
Please note that approximately 250,000 people were living in the "no go" zone prior to the most recent hostilities. The "no go" area covers about 162 square kilometres or 44 percent of the total area of the Gaza Strip. Interestingly, prior to the most recent hostilities, the whole of Palestine , including the West Bank, was the 15th most densely populated state in the world. In 2013, the Gaza Strip had 1,701,437 citizens living in a total area of 365 square kilometres for a total population density of 4661 persons per square kilometre. Now that 162 square kilometres are classified as a "no go" zone, the population density rises as high as 8381 persons per square kilometre, which would move it into third place among the world's most densely populated states. By way of comparison, the population density of the United States is 32.41 persons per square kilometre.
According to the most recent update, an average of 2000 internally displaced persons (IDPs) are living in each of the 82 United Nations Relief and Works Agency (UNRWA) shelters, located in schools, that normally have a capacity to accommodate 500 people. In total, the United Nations is sheltering 182,604 IDPs in the 82 schools or roughly 10 percent of Gaza's entire population. These "shelters" are not designated as living spaces and, as such, have inadequate water sanitation and hygiene facilities. The UNRWA is putting in place plans to prevent an outbreak of head lice and scabies. Unfortunately, for many of the IDPs, when hostilities cease, they will have no home to return to as you can see in this video:
As a result of the ongoing hostilities, more than half of the schools used as shelters have been damaged and will require both minor and major repairs before the new school year starts.
On top of the recent IDPs, keep in mind that over half a million Palestinian refugees live in the eight recognized Palestine refugee camps. Eighty percent of Gaza's population relies on international assistance for their daily lives.
The United Nation's most recent report shows that there were 68 rockets and 88 mortar shells fired into Israel and 161 missiles, 450 navy shells and 1392 tank shells fired into Gaza today. A total of 49 houses were bombarded.