I’ve always been supportive of efforts to share data. For me, it’s a bit selfish, because I want to find interesting real world examples to use in teaching and on my web pages. But the issue goes way beyond this, of course. Sharing data is an ethical imperative, especially for federally funded research or research that relies on volunteer subjects. It has led to many important discoveries beyond the realm of the original context in which the data was collected. In order for data sharing to be effective, you need to embrace four guiding principles: your data needs to findable, accessible, interoperable, and re-usable. This paper highlights those principles and offers some current examples of data sharing systems.