Simḥat Torah means “the joy of Torah” and is the name for the day on which the annual cycle of Torah readings begins and ends.
There are customs in order to prepare for Rosh Hashanah, including Selichot, physical changes in the synagogue, and immersing in the mikveh.
Tahanun is the name for a series of penitential prayers that follow the Amidah during the Morning and Afternoon Services.