19.7.2016 EN Official Journal of the European Union L 194/13 Article 4 Definitions For the purposes of this Directive, the following definitions apply: (1) ‘network and information system’ means: (a) an electronic communications network within the meaning of point (a) of Article 2 of Directive 2002/21/EC; (b) any device or group of interconnected or related devices, one or more of which, pursuant to a program, perform automatic processing of digital data; or (c) digital data stored, processed, retrieved or transmitted by elements covered under points (a) and (b) for the purposes of their operation, use, protection and maintenance; (2) ‘security of network and information systems’ means the ability of network and information systems to resist, at a given level of confidence, any action that compromises the availability, authenticity, integrity or confidentiality of stored or transmitted or processed data or the related services offered by, or accessible via, those network and information systems; (3) ‘national strategy on the security of network and information systems’ means a framework providing strategic objectives and priorities on the security of network and information systems at national level; (4) ‘operator of essential services’ means a public or private entity of a type referred to in Annex II, which meets the criteria laid down in Article 5(2); (5) ‘digital service’ means a service within the meaning of point (b) of Article 1(1) of Directive (EU) 2015/1535 of the European Parliament and of the Council (1) which is of a type listed in Annex III; (6) ‘digital service provider’ means any legal person that provides a digital service; (7) ‘incident’ means any event having an actual adverse effect on the security of network and information systems; (8) ‘incident handling’ means all procedures supporting the detection, analysis and containment of an incident and the response thereto; (9) ‘risk’ means any reasonably identifiable circumstance or event having a potential adverse effect on the security of network and information systems; (10) ‘representative’ means any natural or legal person established in the Union explicitly designated to act on behalf of a digital service provider not established in the Union, which may be addressed by a national competent authority or a CSIRT instead of the digital service provider with regard to the obligations of that digital service provider under this Directive; (11) ‘standard’ means a standard within the meaning of point (1) of Article 2 of Regulation (EU) No 1025/2012; (12) ‘specification’ means a technical specification within the meaning of point (4) of Article 2 of Regulation (EU) No 1025/2012; (13) ‘internet exchange point (IXP)’ means a network facility which enables the interconnection of more than two independent autonomous systems, primarily for the purpose of facilitating the exchange of internet traffic; an IXP provides interconnection only for autonomous systems; an IXP does not require the internet traffic passing between any pair of participating autonomous systems to pass through any third autonomous system, nor does it alter or otherwise interfere with such traffic; (14) ‘domain name system (DNS)’ means a hierarchical distributed naming system in a network which refers queries for domain names; (1) Directive (EU) 2015/1535 of the European Parliament and of the Council of 9 September 2015 laying down a procedure for the provision of information in the field of technical regulations and of rules on Information Society services (OJ L 241, 17.9.2015, p. 1).