Buddhism has been from its inception primarily a tradition of renunciation and monasticism. Within the monastic framework (called the Vinaya) of the sangha regular confession of wrongdoing to superiors (elders; Pali: Thera) is mandatory. In the sutras of the Pali Canon Bhikkhus confessed their wrongdoing to the Buddha himself. That part of the Pali Canon called the Vinaya requires that monks confess their individual sins before the bi-weekly convening for the recitation of the Patimokkha.
In Catholic teaching, the Sacrament of Penance is the method of the Church by which individual men and women confess sins committed after baptism and have them absolved by God through the administration of a Priest. The Catholic rite, obligatory at least once a year for serious sin, is usually conducted within a confessional box, booth or reconciliation room. This sacrament is known by many names, including penance, reconciliation and confession (Catechism of the Catholic Church, Sections 1423-1442). While official Church publications usually refer to the sacrament as "Penance", "Reconciliation" or "Penance and Reconciliation", many laypeople continue to use the term "Confession" in reference to the Sacrament.
For the Catholic Church, the intent of this sacrament is to provide healing for the soul as well as to regain the grace of God, lost by sin. A perfect act of contrition, wherein the penitent expresses sorrow for having offended God and not out of fear of eternal punishment, even outside of confession removes the eternal punishment associated with mortal sin but a Catholic is obliged to confess his or her mortal sins at the earliest opportunity. In theological terms, the priest acts in persona Christi and receives from the Church the power of jurisdiction over the penitent. The Council of Trent (Session Fourteen, Chapter I) quoted John 20:22-23 as the primary Scriptural proof for the doctrine concerning this sacrament, but Catholics also consider Matthew 9:2-8, 1 Corinthians 11:27, and Matthew 16:17-20 to be among the Scriptural bases for the sacrament.
The Catholic Church teaches that sacramental confession requires three "acts" on the part of the penitent: contrition (sorrow of the soul for the sins committed), disclosure of the sins (the 'confession'), and satisfaction (the 'penance', i.e. doing something to make amends for the sins). The basic form of confession has not changed for centuries, although at one time confessions were made publicly.
Typically, the penitent begins sacramental confession by saying, "Bless me Father, for I have sinned. It has been since my last confession." The penitent must then confess what he/she believes to be grave and mortal sins, in both kind and number, in order to be reconciled with God and the Church. The sinner may also confess venial sins; this is especially recommended if the penitent has no mortal sins to confess. According to the Catechism, "without being strictly necessary, confession of everyday faults (venial sins) is nevertheless strongly recommended by the Church. Indeed the regular confession of our venial sins helps us form our conscience, fight against evil tendencies, let ourselves be healed by Christ and progress in the life of the Spirit. By receiving more frequently through this sacrament the gift of the Father's Mercy, we are spurred to be merciful as He is merciful". "When Christ's faithful strive to confess all the sins that they can remember, they undoubtedly place all of them before the divine mercy for pardon." As a result, if the confession was good, "the sacrament was valid" even the penitent inadvertently forgot some mortal sins, which are forgiven as well. As a safeguard not to become something like "subconsciously inadvertent" to avoid saying some sins, these must be confessed in the next confession (if the penitent then remembers them; or generally in the first confession in which they are remembered). Even then it is allowed, however allowed, and even, except for certain devotional purposes, generally sensible to concentrate in one's examination of conscience on the time since the last Confession.