A Creative Commons (CC) license is used when a creator wants to give other people the right to share, use, and build upon a work that they have created. CC provides a creator flexibility (for example, they might choose to allow only non-commercial uses of a given work) and protects the people who use or redistribute a creator's work from concerns of copyright infringement as long as they abide by the conditions that are specified in the license by which the author distributes the work. - Wikipedia
Attribution (by)
All CC licenses require that others who use your work in any way must give you credit the way you request, but not in a way that suggests you endorse them or their use. If they want to use your work without giving you credit or for endorsement purposes, they must get your permission first.
ShareAlike (sa)
You let others copy, distribute, display, perform, and modify your work, as long as they distribute any modified work on the same terms. If they want to distribute modified works under other terms, they must get your permission first.
NonCommercial (nc)
You let others copy, distribute, display, perform, and (unless you have chosen NoDerivatives) modify and use your work for any purpose other than commercially unless they get your permission first.
NoDerivatives (nd)
You let others copy, distribute, display and perform only original copies of your work. If they want to modify your work, they must get your permission first.
From the Creative Commons site.
Make sure your visualizations contain images that are free to use. The links below offer a number of royalty free images.
Government Organizations (such as NASA, NOAA, CDC/Public Health Image Library, Department of Agriculture, etc.)
Museums
University Digital Repositories
"The vast majority of music that you're familiar with is subject to copyright. Artists want to protect their music and be sure that they're getting paid whenever it gets used. And rightfully so! They put in a lot of hard work to create some of your favorite songs."
