While science has always been open – indeed openness is critical to the modern scientific enterprise – there are concerns, and some anecdotal evidence, that the processes for producing research and diffusing its results have become less open. There are several reasons. First, science is increasingly data-driven and expensive, but access to scientific data is often subject to administrative, legal and privacy regulations. Access also requires adequate information and communication technology (ICT) infrastructure. Other limits on openness in science include policies and practices at universities that place a premium on patenting over publishing and weak incentives for researchers to share data. This can also act as a barrier to the replication and validation of scientific experiments. Finally, the policies and practices of scientific publishers that limit web-based access to research results may also make access to scientific data less open.