This Practice Note summarises the EU Guidelines on the applicability of Article 101 of the Treaty on the Functioning of the European Union (TFEU) to horizontal co-operation agreements (Horizontal Guidelines). The Practice Note also refers to the revised Research and Development Block Exemption Regulation (R&D BER) and the Specialisation Block Exemption Regulation (SBER), together referred to as the Horizontal Block Exemption Regulations (HBERs). The Horizontal Guidelines provide guidance on how to apply the HBERs and how to assess other types of cooperation agreements, such as R&D agreements, production agreements, purchasing agreements, commercialisation agreements, information exchange, standardisation agreements, standard terms and sustainability agreements. NOTE—This Practice Note does not cover the HBERs or sustainability agreements in full detail. See the following separate Practice Notes: EU competition law and research and development agreements, EU competition law and joint production agreements and Sustainability and EU competition law. Introduction What is a horizontal agreement? A ‘horizontal agreement’ is an agreement entered into by separate undertakings that operate at the same level of the supply chain (ie actual or