What is an ally?

This article starts by providing a definition of the word “ally”, with the originality of including non-state entities in the concept. The article then proposes a typology based on the analogy of a pack of cards, identifying four types of ally—the ally of spades, with whom entities form an alliance because they are afraid of it, the ally of clubs, chosen because it is needed, the ally of hearts, with whom the entity has shared values, and the ally of diamonds, with whom allies are bound by legal constraint, for example by treaty. In the second part, the article investigates the winning combinations that distinguish a “good” ally and thereby determine the effectiveness of an alliance