Scientists and, more generally end users of computer systems, need to be able to trust the data they use. Understanding the origin or provenance of data can provide this trust. Attempts have been made to develop systems for recording provenance, however, most are not generic and cannot be applied in a general manner across different systems and different technologies. Moreover, many existing systems confuse the concept of provenance with its representation. In this article, we discuss an open, technology neutral model for provenance. The model can be applied across many different systems and makes the important distinction between provenance and the way it can be generated from a concrete representation of process. The model is described and applied to a grid-based example bioinformatics application.