A catalogue is the metadata of a database which stores information about its schema (how the information is laid out).
For a simple analogy, consider the header row of a spreadsheet. The whole spreadsheet is a database in tabular format, and the header row above the data defines the structure (schema). The header row acts as the catalogue for this database. A typical SQL database would store things a bit differently, but this example illustrates the concept.
- Import § More information, for links to large scale data imports
- For information about the OpenStreetMap database organization, see the article "Database"