Creative Commons licences allow creators to permit others to legally build upon and share work.
Creative Commons (CC) licences are widely used, for example:
CC material must be acknowledged (see below for how to do this).
Creative Commons licences allow some rights to be reserved, and some to be waived, by the creator (commercial use may not be permitted, for example), rather than having 'All rights reserved' as is the case with copyrighted works.
How material may be used will depend on what right the creator has reserved and which they have waived - see the 'Licence Conditions' box below.
Creative Commons is a US non-profit company.
Each right that creators may reserve, or waive, has initials.
The creator of the material must be attributed (acknowledged).
Users may copy, distribute, display, perform, and modify the work, but must licence the work with the same (and not a more restrictive) licence. If they want to use a more restrictive licence they must obtain the creator's permission.
Work cannot be re-used commercially without permission. Normally educational uses are non-commercial.
Work may be re-used, but not modified without permission.
The initials may be combined. For example:
The Creative Commons website has examples of best practice for acknowledgment, and suggests acknowledging this image like this:
"Creative Commons 10th Birthday Celebration San Francisco" by tvol is licensed under CC BY 2.0
This or a similar format is fine, with links to the material and the licence terms. You could also state the website the material is taken from, as has been done in the image credits of this guide (which use a slightly different format).
We would also recommend, certainly for academic work, giving the date the material was accessed at the end, as this acts as an assurance that the webpage existed if it should disappear:
"Creative Commons 10th Birthday Celebration San Francisco" by tvol is licensed under CC BY 2.0 (Accessed 02/09/2016)