ODbl

ODbL stands for the Open Data Commons Open Database License. It is a copyleft license designed for databases and data sets, administered by the Open Data Commons, an initiative of the Open Knowledge Foundation. The license enables free use, modification, and redistribution of the database, including for commercial purposes, as long as the terms are followed.

The two core requirements are attribution and share-alike. Attribution obliges users to credit the original data producers in the manner specified by the licensor. Share-alike requires that if you distribute a derivative database or a modified version, you must license it under the ODbL and provide the same terms to downstream users.

The license also addresses produced works and notices. When a work uses data from an ODbL-licensed database, you must ensure that the provenance of the data is preserved and that appropriate attribution and license information accompanies the distribution. In many cases, distributors must offer access to the underlying data under the ODbL, and retain the original notices and license text.

ODbL is widely used for geospatial and other large datasets. OpenStreetMap is the most prominent example of a project using the license, helping to ensure that map data remains openly accessible while requiring attribution and the sharing of derivative data under the same terms.

As a data license, ODbL provides a permissive framework for openness while imposing structured conditions to protect provenance, attribution, and continued freedom for downstream users.