From Wikipedia:-
The restrictions on movement and goods in Gaza imposed by Israel date back to the early 1990s. In 2005, Israel unilaterally withdrew its military forces from Gaza, dismantled its settlements, and implemented a temporary blockade of Gaza. The blockade became indefinite after the 2007 Hamas takeover. Egypt also began its blockade of Gaza in 2007.
Despite the Israeli disengagement, Gaza is still considered occupied by Israel under international law. The current blockade prevents people and goods from freely entering or leaving the territory, leading to Gaza often being called an "open-air prison".
Despite the 2005 Israeli disengagement from Gaza, the United Nations, international human rights organisations, and the majority of governments and legal commentators consider the territory to be still occupied by Israel, supported by additional restrictions placed on Gaza by Egypt.
Israel maintains direct external control over Gaza and indirect control over life within Gaza: it controls Gaza's air and maritime space, as well as six of Gaza's seven land crossings. It reserves the right to enter Gaza at will with its military and maintains a no-go buffer zone within the Gaza territory. Gaza is dependent on Israel for water, electricity, telecommunications, and other utilities. The extensive Israeli buffer zone within the Strip renders much land off-limits to Gaza's inhabitants. The system of control imposed by Israel was described in the fall 2012 edition of International Security as an "indirect occupation".
The European Union (EU) considers Gaza to be occupied.
The international community regards all of the Palestinian territories including Gaza as occupied. Human Rights Watch has declared at the UN Human Rights Council that it views Israel as a de facto occupying power in the Gaza Strip, even though Israel has no military or other presence, because the Oslo Accords authorize Israel to control the airspace and the territorial sea.