Penance is any act or a set of actions done out of repentance for sins committed, as well as an alternate name for the Catholic, Lutheran, Eastern Orthodox, and Oriental Orthodox sacrament of Reconciliation or Confession. It also plays a part in confession among Anglicans and Methodists, in which it is a rite, as well as among other Protestants. The word penance derives from Old French and Latin paenitentia, both of which derive from the same root meaning repentance, the desire to be forgiven (in English see contrition). Penance and repentance, similar in their derivation and original sense, have come to symbolize conflicting views of the essence of repentance, arising from the controversy as to the respective merits of "faith" and "good works". Word derivations occur in many languages.

According to dictionary definitions, the primary meaning of penance is the deeds done out of penitence, which also focuses more on the external actions than does repentance which refers to the true, interior sorrow for one's hurtful words or actions. Only repentance implies a purpose of amendment which means the resolve to avoid such hurtful behavior in the future. The words "true" and "firm" might be added to all but penance, to specify the depth of change in one's hurtful attitude. Contrition is the state of feeling remorseful, and can describe both the show of regret to the deepest and firmest sorrow for one's wrongdoings.