Aliyah (US: , UK: ; Hebrew: עֲלִיָּה ʿălīyyā, lit. 'ascent') is the immigration of Jews from the diaspora to, historically, the geographical Land of Israel, which is in the modern era chiefly represented by the State of Israel. Traditionally described as "the act of going up" (towards the Jewish holy city of Jerusalem), moving to the Land of Israel or "making aliyah" is one of the most basic tenets of Zionism. The opposite action—emigration by Jews from the Land of Israel—is referred to in the Hebrew language as yerida (lit. 'descent'). The Law of Return that was passed by the Israeli parliament in 1950 gives all diaspora Jews, as well as their children and grandchildren, the right to relocate to Israel and acquire Israeli citizenship on the basis of connecting to their Jewish identity.

For much of their history, most Jews have lived in the diaspora outside of the Land of Israel due to various historical conflicts that led to their persecution alongside multiple instances of expulsions and exoduses, with the most recent such event being the Jewish–Roman wars. Despite its historical value as a national aspiration for the Jewish people, aliyah was acted upon by few prior to the rise of a national awakening among Jews worldwide and the subsequent development of the Zionist movement in the late 19th century; the large-scale immigration of Jews to Palestine had consequently begun by 1882. Since the Israeli Declaration of Independence in 1948, more than 3 million Jews have made aliyah. As of 2014, Israel and the Israeli-occupied territories contain approximately 42.9 percent of the world's Jewish population.