Libraries, museums and archives have a wealth of information about their collections that is too often locked away in isolated silos, according to open data expert Owen Stephens who was speaking at Internet Librarian International.Opening up access to library data can enable others to innovate in unforeseen ways, adding value to the originating organisation as well as to the wider community.Passing a box of chocolates round the audience, Stephens described a continuum of openness, rather than a binary 'open/closed' scenario. In an ideal world, data would be openly licensed, open accessible, openly discoverable and openly connected.Stephens described the Discovery initiative, which aims to improve resource discovery by establishing a clear set of principles and practices for the publication and aggregation of open, reusable metadata.A likely outcome of openness is that external users will find valuable new ways of engaging with the data. For example, Cambridge University documented the APIs available for their data and a student then built an iPhone app which enables users to find out whether a book is available in the library nearest to their current location.To quote Rufus Pollock, co-founder of the Open Knowledge Foundation, "the coolest thing to do with your data will be thought of by someone else".