In religious and magical practice, insufflation and exsufflation are ritual acts of blowing, breathing, hissing, or puffing that signify variously expulsion or renunciation of evil or of the devil (the Evil One), or infilling or blessing with good (especially, in religious use, with the Spirit or grace of God).

In historical Christian practice, such blowing appears most prominently in the liturgy, and is connected almost exclusively with baptism and other ceremonies of Christian initiation, achieving its greatest popularity during periods in which such ceremonies were given a prophylactic or exorcistic significance, and were viewed as essential to the defeat of the devil or to the removal of the taint of original sin.

Ritual blowing occurs in the liturgies of catechumenate and baptism from a very early period and survives into the modern Roman Catholic, Greek Orthodox, Maronite, and Coptic rites. Catholic liturgy post-Vatican II (the so-called novus ordo 1969) has largely done away with insufflation, except in a special rite for the consecration of chrism on Maundy Thursday. Protestant liturgies typically abandoned it very early on. The Tridentine Catholic liturgy retained both an insufflation of the baptismal water and (like the present-day Orthodox and Maronite rites) an exsufflation of the candidate for baptism, right up to the 1960s:

[THE INSUFFLATION] He breathes thrice upon the waters in the form of a cross, saying: Do You with Your mouth bless these pure waters: that besides their natural virtue of cleansing the body, they may also be effectual for purifying the soul.

THE EXSUFFLATION. The priest breathes three times on the child in the form of a cross, saying: Go out of him...you unclean spirit and give place to the Holy Spirit, the Paraclete.