The article presents cyberspace and its security as one of the most important tasks and challenges of states and organizations associating them. Definitions and concepts related to cybersecurity are presented. Cybersecurity is one of the most important and increasingly important components of national security. State cybersecurity covers the security of ICT systems and the data processed in them, used in the digital space, both by the administration, public and economic entities, and by citizens. Cyberspace is an area of confrontation not only with other countries, but also with hostile organizations, such as extremist and terrorist groups or organized crime groups. The article addresses the issues of responsibility for ensuring the cybersecurity of ICT systems of key national entities, organizations and institutions and its impact on the development of states' activities. The responsibility of individual countries for ensuring the security of their cyberspace was indicated. Ensuring the security of the country in cyberspace, including the security of its cyberspace, is one of the basic tasks in the field of state security. Cybersecurity should be implemented both through the development of defensive capabilities (including the protection of entities operating in cyberspace and the cyberspace itself) and offensive. The article presents the international (European) and national legal context of cybersecurity by indicating the relevant legal regulations, such as EU directives and national laws and regulations, and strategic documents - such as security and cybersecurity strategies, both for the European Union and Poland. The state of cyberspace security of the Republic of Poland was also presented in terms of the number and types of security incidents and events, and the state of vulnerability of ICT systems of state institutions and business entities. The review is based on the analysis and synthesis of information presented in the annual CSIRT GOV and CSIRT NASK reports, responsible for the security of the most important, from the national security perspective, ICT systems in Poland.