The Amidah (Hebrew: תפילת העמידה, Tefilat HaAmidah "The Standing Prayer"), also called the Shmoneh Esreh (שמנה עשרה, Shmoneh Esreh "The Eighteen," in reference to the original number of constituent blessings, there are now nineteen), is the central prayer of the Jewish liturgy. This prayer, among others, is found in the siddur, the traditional Jewish prayer book. As Judaism's central prayer, the Amidah is often designated simply as tefila (תפילה, "prayer") in Rabbinic literature.

Observant Jews recite the Amidah at each of three prayer services in a typical weekday: morning, afternoon, and evening. A special abbreviated Amidah is also the core of the Mussaf ("Additional") service that is recited on Shabbat (the Jewish Sabbath), Rosh Chodesh (the day of the New Moon), and Jewish festivals, after the morning Torah reading, with various forms of the Amidah that depend on the occasion. The typical weekday Amidah actually consists of nineteen blessings, though it originally had eighteen; when the Amidah is modified for specific prayers or occasions, the first three blessings and the last three remain constant, framing the Amidah used in each service, while the middle thirteen blessings are replaced by blessings specific to the occasion.