Chazal or Ḥazal (Hebrew: חז״ל), an acronym for the Hebrew "Ḥakhameinu Zikhronam Liv'rakha" (חכמינו זכרונם לברכה, "Our Sages, may their memory be blessed"), refers to all Jewish sages of the Mishna, Tosefta and Talmud eras, spanning from the times of the final 300 years of the Second Temple of Jerusalem until the 7th century CE, or c. 250 BCE – c. 625 CE.
Chazal are generally divided according to their era and the main writing done in that era:
Until the end of the Savoraim era, Chazal had the authority to comment on the Torah according to the Talmudical hermeneutics standards required by the Law given to Moses at Sinai, sometimes even expounding a word or phrase outside its plain and ordinary sense. Nowadays in Orthodoxy, this authority is not delegated to the current generation's sages, and thus the Torah can not be commentated on, in matters concerning the halakha ("Jewish Law"), if it contradicts Chazal's commentary.
Until the middle of the Tannaim era, when there was a Sanhedrin (a High Court of Jewish law), Chazal had also the authority to decree restrictions and to enact new religious regulations, in any matter they saw fit, concerning issues that were not included in the written Torah, or were not delivered at Mount Sinai. These rabbinical mitzvot ("commandments") include the holidays of Purim and Hanukkah, the laws of muktzeh ("set-aside items") on Shabbat, the ritual washing of one's hands (netilat yadayim) before eating bread, the construction of eruvim (liminal gateways), and the institution of the current schedule of daily prayer services – shacharit (morning prayer), mincha (afternoon prayer), and ma'ariv (evening prayer).