The practice of requiring penitents to give public satisfaction for their sins as a condition for absolution and reconciliation with the Church. In vogue up to the early Middle Ages, public penance could be either solemn or not, depending on the gravity of the offense and the amount of scandal given.
When public penance was also solemn, the reason had to be a grave one. Among the public crimes that might be subject to solemn penance, the most common were adultery, apostasy, fornication, and murder, including abortion. A historic example of public penance was Henry II's walking barefoot in 1174 to the shrine of St. Thomas of Bucket, to expiate his part in the murder of the archbishop. The more common practice was to limit solemn penance to those crimes that gave such scandal as seemed to call for proportionate expiation.
More generally, public penance was not solemn. The person would secretly confess some grave sin from which he was absolved by a priest. His satisfaction would be an external penance from which others might conclude the nature of the sin, but there was no formal identification as a public sinner.