Iconoclasm is the rejection, prohibition, or destruction of sacred images. In Christian history the term especially denotes the Byzantine iconoclastic controversies of the eighth and ninth centuries.
The controversy
Iconoclast emperors and churchmen opposed the veneration of icons, while defenders argued that the Incarnation changed the theological question: because the Word truly became visible flesh, Christ may be depicted according to His humanity.
Seventh Ecumenical Council
The Second Council of Nicaea in 787 distinguished the honour or veneration offered to images from the worship due to God alone. Honour shown to an icon passes to its prototype. The definitive restoration of icons in Constantinople in 843 is commemorated as the Triumph of Orthodoxy.