Open Access to scientific information, transparency of research processes and data is one of the most important conditions for the progress of science and scientific communication, the basis of international collaboration of researchers globally. The COVID-19 global pandemic has once again highlighted the need for open, efficient and equal access to scientific information for researchers, regardless of geographical, gender or any other constraints, promoting the exchange of scientific knowledge and data, scientific cooperation and scientific decision-making, knowledge and open data. The Internet has radically changed scientific communication, particularly on the model of peer-reviewed scientific journals and the way readers find and access the scientific information. Digital access is now the norm, thanks to the Open Access model. Although 20 years have passed since the announcement of the Budapest Open Access Initiative, and despite many achievements and advantages, there are still obstacles to the implementation of this model, there is some resistance from commercial publishers and other providers, and discussions continue in the academia world. The Open Access model is already supported by various strategies, policies, platforms, applications but is not yet established. Various business models for scientific journals are still being tested, a culture of preprints is being formed, and discussions are underway on the ethics of scientific publications, intellectual property, the need to finance the dissemination of research results, and so on. Various platforms and applications are being developed to help researchers “discover” research results. Nevertheless, this is not enough: it is important to “discover” not only the results but also the research data, allowing them be used for further research in the global world. Thus, the concepts and practices of Open Science, Open Data, development of research infrastructures, etc., are developing quite rapidly. The article considers the main stages of this 20-year path and outlines the main components and trends of the current stage. Emphasis is placed on the need to form a culture of Open Science and create incentives for its implementation, promoting innovative methods of Open Science at different stages of the scientific process, the needs of European integration of Ukrainian e-infrastructure development, the need for socio-cultural and technological change. The main international and domestic practices and projects in Open Access and Open Science, particularly the National Repository of Academic Texts and the National Plan of Open Science draft, are considered. The role of libraries and librarians in implementing the principles of Open Access and Open Science is emphasized.