The Rafah crossing between the Gaza Strip and Egypt is the sole route for aid to enter Gaza directly from outside Israel and the only exit that does not lead to Israeli territory.
It has become a focus in the intensifying conflict between Israel and the Palestinian militant group Hamas, as hundreds of thousands of Palestinians have headed towards south Gaza after Israel warned them to leave Gaza City and the enclave's north.
WHERE IS THE RAFAH CROSSING AND WHO CONTROLS IT?
The crossing is at the south of the Gaza Strip, a narrow slither of land that is home to 2.3 million people and wedged between Israel, Egypt and the Mediterranean Sea.
The crossing is controlled by Egypt.
WHY IS THE RAFAH CROSSING SO IMPORTANT IN THIS CONFLICT?
In response to a devastating cross-border infiltration by Hamas fighters on Oct. 7 that killed over 1,300 Israelis, Israel has imposed a "total blockade" of Gaza, cutting off electricity to the territory and stopping all supplies of food and fuel.
That means the only likely route for humanitarian aid to enter Gaza is via Rafah from Egypt's Sinai region. It is also the only exit point for Gaza residents seeking to flee.
Foreign passport holders are expected to be allowed out under any deal to reopen the crossing, and have therefore headed in recent days to the vicinity, seeking to exit.
WHY IS ACCESS ACROSS RAFAH RESTRICTED?
Egypt is wary of insecurity near the border with Gaza in northeastern Sinai, where it faced an Islamist insurgency that peaked after 2013 and has now largely been suppressed.
Since Hamas took control in Gaza in 2007, Egypt has helped enforce a blockade of the enclave and heavily restricted the flow of people and goods. Like the main crossings with Israel, restrictions have sometimes been eased but not lifted, and travellers need security clearance and lengthy checks to pass.
In 2008, tens of thousands of Palestinians crossed into Sinai after Hamas blasted holes in border fortifications, prompting Egypt to build a stone and cement wall.
Egypt has acted as a mediator between Israel and Palestinian factions during past conflicts and periods of unrest. But in those situations it has also locked down the border, allowing aid to enter and medical evacuees to leave but preventing any large-scale movement of people.
Even as Israel pursues its heaviest and most unrelenting bombardment of Gaza in response to the Hamas assault, Egypt has shown no sign so far that its approach will change. More than 2,800 Palestinians have been killed by Israeli bombing strikes.
WHAT EFFORTS ARE BEING MADE TO OPEN THE BORDER?
The United Nations has urged Israel to avert a "humanitarian catastrophe" in Gaza, warning that food, fuel and even drinking water supplies are running dangerously low.
Hospitals say they are struggling to cope with the wounded as back-up generators run low on fuel.
U.S. Secretary of State Antony Blinken said on Tuesday the United States and Israel had agreed to develop a plan to get humanitarian aid to civilians in Gaza without benefiting Hamas.
WHY ARE ARAB STATES SO RELUCTANT TO TAKE IN PALESTINIANS?
Egypt, the only Arab state to share a border with Gaza, and Jordan, which flanks the Israeli-occupied West Bank, have both warned against Palestinians being forced off their land.
Egyptian President Abdel Fattah al-Sisi has said it is vital that Palestinians "remain steadfast and present on their land," while Jordan's King Abdullah warned "against any attempt to forcibly displace Palestinians from all Palestinian territories or cause their internal displacement".
For Arabs and Palestinians, the idea of leaving or being driven out of territory where they want to forge a state carries echoes of the "Nakba", or "catastrophe", when many Palestinians fled or were forced from their homes during the 1948 war that accompanied Israel's creation.
Israel contests the assertion it drove Palestinians out, saying it was attacked by five Arab states after its creation.
Some 700,000 Palestinians, half the Arab population of what was British-ruled Palestine, were dispossessed and displaced, many spilling into neighbouring Arab states where they and their descendants remain. Many still live in refugee camps.
As a result, many Palestinians say they do not want to leave Gaza - from which Israel withdrew in 2005 after a 38-year occupation - even as this latest conflict has escalated.
