From
MyJewishLearning.com:
While confessing sins and making amends are possible at any time, Yom Kippur focuses on confession. Known by the Hebrew word vidui, the Yom Kippur confession is a public and communal act, recited in the plural. Forgiveness is asked for horrendous sins that the vast majority of individuals did not commit. There are two forms of confession on Yom Kippur; the long confession called the "al chet" (for the sin) and the short alphabetic confession known simply as the vidui (confession).
