If you are re-using data collected by other researchers, follow these two rules to be a courteous consumer of that data.
1. Look at the license on the dataset - The license will tell you what you can (and can't) do with the data. Common licenses include a Creative Commons license or an Open Data Commons License. If the dataset has license, you should follow the terms of the license carefully. (Not all datasets have a license.)
Below are the icons used to denote the six different Creative Commons licenses. If you see one of these icons, this website will help you to understand how you can and can't re-use the data.
Often, the dataset's license is written in the text, rather than using the icon. See the example below from Zenodo, a discipline agnostic data repository. In this example, you can click on the Creative Commons link on the right toolbar to get more info on the dataset's license.
Source: zenodo.org/record/322936#.WLmc41UrJQJ
2. Cite the dataset - When re-using a dataset in a publication or presentation, give the complete citation for the dataset (like you would for a scholarly publication). See more information on the Citing Data sets page.
At a minimum, the citation should include: