Vandalism (capitalized) is the spirit or conduct of the Vandals; thus, ferocious cruelty; hostility to the arts and literature, or willful destruction or defacement of their monuments.
Throughout history, the destruction of monuments of a previous government or power has been one of the greatest symbols of the transition of power. Recent cases of Vandalism include the toppling and destruction of Soviet monuments after the fall of the Soviet Union and the Taliban destruction of Buddhist statuary in Afghanistan.
Uncapitalized, vandalism is willful wanton and malicious destruction of the property of others.
The term is usually generalized to include undesired, non-destructive unauthorized modification (e.g. defacement) of property.
World Wide Web vandalism
With the rise and development of the World Wide Web came unauthorized and undesired modification of webpages.