ScienceBase uses the basic informational unit of an "item" to describe everything in the catalog. Items may describe datasets, projects, publications, maps, and any number of other types of things. All items share a few basic attributes, such as a title and abstract, and item descriptions (the metadata) may be extended to include other attributes. For example, a project may be described by core metadata fields (title, abstract, contacts) and the Project Extension may be applied to add unique metadata fields applicable to projects, such as budget information, project status and duration. ScienceBase items are described by metadata, and may include geospatial attributes, uploaded files, and website URLs (for navigation, data download and connections to related websites).