Cultural and scientific data cannot be understood without knowledge about the provenance (the origin, context or history). Provenance provides a critical foundation for assessing authenticity, enabling trust, and allowing reproducibility. Provenance metadata are data describing objects, people, places, times which are causally related by events. They are event centric and must be described in a historical order to ensure that there are no references to non-existent (non-recorded) events or objects. Nowadays provenance has become even more critical in the web environment where data are sourced not only from established archives, but from many mixed credentialed providers.