The collection forms the foundation of the Natural History Museum Rotterdam. It is used in exhibitions, museum education, research and publications. The collection is estimated to hold approximately 400,000 samples (collection units), dating back to as early as 1859. Arthropods (predominantly insects: butterflies and beetles) and molluscs (bivalves and gastropods) make up about 85% of the collection. The collection focuses on The Netherlands and Europe, but in some taxonomic groups (such as molluscs), the coverage is global. Vertebrates, including fossils, amount to 9% of the collection and the herbarium takes just over 5%. Over 85% of the collection is digitized and accessible via a public database; the data can also be accessed directly through GBIF. The Natural History Museum Rotterdam has an active collection policy which results in a continuously growing collection that is available to scientists worldwide; please enquire for details.