The United Nations General Assembly passed resolution 194 in December 1948, as part of an attempt to deal with the region of Palestine as it stood at the end of the 1948 Arab-Israeli war.
Article 11 of the resolution, which consists of a total of 15 articles, is quoted as the "right of return", and "resolves that the refugees wishing to return to their homes and live at peace with their neighbours should be permitted to do so at the earliest practicable date".
Article 11 also states that compensation should be paid to those who choose not to return, as well as for damage to property.
Israel accepted the resolution, essentially because acceptance of Resolution 194 was made a condition of the new state of Israel's entry into the UN.
Many Arab states, including Egypt and Syria, voted against the resolution.
There has been much dispute over interpretation of the resolution, with some saying it cannot be applied in a practical way and would threaten the existence of Israel.
Israel's government is keen for the country to remain a majority Jewish state and a flood of returning refugees might put this in jeopardy.
Many cite security concerns, pointing out that Article 11 only calls for the right of return to be implemented if refugees intend to "live at peace with their neighbours". Plenty in Israel argue that this is not the case.
Some Israeli critics accept the "right of return", but argue that Israel should offer sufficient compensation to dissuade Palestinians from taking it up.
However, the "right of return" remains one of the most serious impediment to any resolution to Arab-Israeli conflict. Many Palestinians, even if they now have established lives elsewhere and may not exercise the right, want to be allowed to return.
It has also been argued that Resolution 194 applies to Jews who fled from Arab lands in the aftermath of the 1948 war, and that they too are entitled to the "right of return".