This piece presents systematically the contributions that the EU courts have made to the understanding of the notion of restriction of competition over the years. It examines, first, the issues around which there is consensus among commentators. It is undisputed, for instance, that a restriction cannot be established without considering the economic and legal context of which a practice is part. This assessment comprises the evaluation of the counterfactual. Secondly, the paper focuses on the issues that remain controversial. In this regard, it appears that the case law is more consistent and sophisticated than commonly conceded. In particular, the EU courts have followed a clear line when examining whether a practice is restrictive by object. Similarly, the relevant case law sheds sufficient light about the elements that are relevant in the context of an analysis of effects.