סְלִיחוֹת Elul · Selichot
Selichot: the prayers of the pre-dawn
Selichot are the prayers of pardon said before dawn, while the world is still quiet. When they begin depends on your community — and both customs are valid.
What they are
Selichah means “pardon.” Selichot are prayers and verses — many built around the Thirteen Attributes of mercy (Exodus 34:6–7) — said in the ashmoret, the last watch of the night. The pre-dawn, the tradition says, is the hour when the heart is most open.
Sephardim: from Rosh Chodesh Elul
Sephardic and Mizrachi communities say Selichot all month, from Rosh Chodesh Elul through Yom Kippur. A whole month of pre-dawns.
Ashkenazim: the week before
Ashkenazic communities begin later: from the close of the Shabbat before Rosh Hashanah, so that there are at least four days of Selichot before the new year. If Rosh Hashanah falls early in the week, they begin a Shabbat earlier.
Sources: Shulchan Aruch, Orach Chaim 581:1 · Exodus 34:6-7 · community minhagim.
My Jewish Day tells you when Selichot begin by your custom, without assuming a single one.