This report explores the case for open science, illustrated by use cases and case studies, spanning academia, start-ups and enterprises. It seeks to explain why public sector and private sector researchers should support open science by highlighting concrete examples of disciplinary breakthroughs that have been fuelled by the sharing of research data, tools and infrastructure. The report draws on discussions and input from an independent consultation group representing research, industry and policy, which is coordinated by Science|Business. It begins by considering how to define open science, before then exploring the progress being made to date and the various obstacles standing in the way of more openness. The next section considers the work of the European Commission and the role of the European Open Science Cloud (EOSC) in making it easier for scientists to share their data, their tools and their methodologies. Finally, the paper outlines some examples of how open science has driven significant steps forward in various fields of research from astrophysics to the development of drugs.