This chapter focuses on attribution from an international law perspective, that is to say the attribution of a conduct to a State or another subject of international law. The attribution, also referred to as the imputation, is the legal operation aiming at determining whether an act or omission is to be characterised as an act of the State under international law. The present chapter deals with the attribution of cyber operations to States. Its structure is mainly articulated around the Articles on State Responsibility adopted by the International Law Commission in 2001, which reflect the norms of customary international law on State Responsibility.