The Authentic Cadence is a widely used cadence, common practically to the point of ubiquity, and describes a V - I chord progression that resolves a musical phrase or piece. Optionally, the V chord can be a V7, and/or be preceded by a IV chord. A list of examples would be very nearly useless - virtually every composition in the Western musical tradition contains this cadence in abundance, right until the point where atonality challenged the entire chord system wholesale. However, there are some interesting patterns to observe; for instance, the first symphony by Ralph Vaughan Williams (1909) uses the V - I progression freely, but in his other eight symphonies there is barely a single clear-cut instance in over six hours of music. Another notable pattern is that in western popular music, while still common, this progression is not ubiquitous; there are many instances of plagal cadences (or just forced looping from a IV chord back to a I chord). Among popular styles, the authentic cadence seems to be more prevalent in east-Asian popular music (though still less than nearly ubiquitous).