Subversion (from Latin subvertere 'overthrow') refers to a process by which the values and principles of a system in place are contradicted or reversed in an attempt to transform the established social order and its structures of power, authority, hierarchy, and social norms. Subversion can be described as an attack on the public morale and, "the will to resist intervention are the products of combined political and social or class loyalties which are usually attached to national symbols. Following penetration, and parallel with the forced disintegration of political and social institutions of the state, these tendencies may be detached and transferred to the political or ideological cause of the aggressor". Subversion is used as a tool to achieve political goals because it generally carries less risk, cost, and difficulty as opposed to open belligerency. Furthermore, it is a relatively cheap form of warfare that does not require large amounts of training. A subversive is something or someone carrying the potential for some degree of subversion. In this context, a "subversive" is sometimes called a "traitor" with respect to (and usually by) the government in power.

Subversion, however, is also often a goal of comedians, artists and people in those careers. In this case, being subversive can mean questioning, poking fun at, and undermining the established order in general.

Terrorist groups generally do not employ subversion as a tool to achieve their goals. Subversion is a manpower-intensive strategy and many groups lack the manpower and political and social connections to carry out subversive activities. However, actions taken by terrorists may have a subversive effect on society. Subversion can imply the use of insidious, dishonest, monetary, or violent methods to bring about such change. This is in contrast to protest, a coup d'état, or working through traditional means in a political system to bring about change. Furthermore, external subversion is where, "the aggressor state attempts to recruit and assist indigenous political and military actors to overthrow their government by coup d’état". If subversion fails in its goal of bringing about a coup it is possible that the actors and actions of the subversive group could transition to insurrection, insurgency, and or guerilla warfare.

The word is present in all languages of Latin origin, originally applying to such events as the military defeat of a city. As early as the 14th century, it was being used in the English language with reference to laws, and in the 15th century came to be used with respect to the realm. The term has taken over from 'sedition' as the name for illicit rebellion, though the connotations of the two words are rather different; sedition suggesting overt attacks on institutions, subversion something much more surreptitious, such as eroding the basis of belief in the status quo or setting people against each other.