A Digital Object Identifier (DOI) is a serial code used to uniquely identify objects. The DOI system is particularly used for electronic documents such as journal articles and it is becoming popular also to uniquely tag datasets.
In the context of Open Science, DOIs are very important as all components of a “research product” (paper, data, software, virtual appliance where the software can be re-used to re-analyse the data, etc.) can be assigned DOIs and an additional DOI can be assigned to the “research product”. Through DOIs, all research products thus become searchable, discoverable and findable.
The Sci-GaIA project strongly promotes the use of DOIs and it has a DOI prefix itself (dx.doi.org/10.15169/sci-gaia:), released by DataCite, to mint DOIs for all its outputs (deliverables, data, etc.). As an example, all records of the Sci-GaIA Open Access Repository have DataCite DOIs.