The Amidah (Hebrew: תְפִלָת הַעֲמִידָה, romanized: Tefilat HaAmidah, lit. 'the Standing Prayer'), also called the Shemoneh Esreh (שְׁמוֹנֶה עֶשְׂרֵה, 'Eighteen'), is an important prayer in Judaism. Religious Jews recite the Amidah during each of the three services prayed on weekdays: Morning (שַׁחֲרִית, Shacharit), afternoon (מִנחָה, Mincha), and evening (מַעֲרִיב, Ma'ariv; also called עַרבִית, Arvit). On Shabbat, Rosh Chodesh (ראש חודש, 'Head [of the] Month'), and Jewish holidays, after the morning Torah reading, a fourth Amidah is recited during Mussaf ( (מוּסָף). Once annually, a fifth Amidah is recited during the Ne'ila (נְעִילָה) service of Erev Yom Kippur. Due to the importance of the Amidah, in the Rabbinic literature it is referred to only as "ha-tefila" (הַתְּפִילָה, 'the prayer').
A precise dating of the Amidah's formalization is not possible. However, Rabban Gamaliel is recorded in tractate Berakhot 28b:12 of the Talmud saying, "Each and every day, a person recites the prayer of eighteen blessings" (i.e., the Shemoneh Esreh), suggesting that the Amidah likely had a fixed formula before the end of the Mishnaic period (c. 220 CE). Furthermore, in Berakhot 28b:23, the Talmud records the formalization of the contemporary nineteen-blessing Amidah by the tanna Shmuel ha-Katan during the same period. Given that the Amidah includes a petition for the reconstruction of the Temple, the Second of which was destroyed in 70 CE, the Amidah's fixing likely occurred between then and the end of the Tannaitic era. Accordingly, in Judaism, to recite the Amidah is a mitzvah d'rabbanan (Jewish Babylonian Aramaic: מִצְוָה דְּרַבָּנָן, lit. 'commandment of [the] Rabbis'), or a commandment of Rabbinic origin.