Interview with Henry Rzepa: Imperial College London, UK, recorded at the BEILSTEIN OPEN SCIENCE SYMPOSIUM (22 – 24 May 2017). Henry Rzepa discusses metadata in chemistry with Carsten Kettner. Before the interview moves on to things chemical, Henry recounts his over 300000 miles of motorbike riding in London visiting the many rivers. The discussion started with the meaning of the term “meta”; in this context metadata refers to the data that are needed to describe data, thus metadata are actually more important and more interesting than the data. The question of format for metadata was raised; whilst the format is not so important, one still needs to query it, so it is necessary to know how to ask the right question. It is important to remember that when building a repository, any mistakes would be permanent. But here, good metadata can help; in the curation of data – correcting errors, bringing it up to date, putting it in a more modern form, and hence giving the data a longer life. Metadata helps make data FAIR; Findable, Accessible, Interoperable and tells you how you can Reuse it. When discussing standards for metadata, Henry raised the issue of understanding what a bond is. Most chemists think they know what a bond is, but in reality probably don’t really know, which means that they are going to need to reach an agreement on how to describe them. In Henry’s view, chemists are like cats, it is very difficult to get more than 4 chemists to agree on anything. But to make things work we need open community efforts. Henry is interested in chemical reactions and their transition states and has modeled them in InChI. For him it is import not to discuss hypothetical or abstract descriptions of how to do something but to actually to try things out, get an example out for the community to use. You have to build real things, and take them a part again – that is how science works.