Attribution is normally required when using someone else's copyrighted work.
Creative Commons (CC) Attribution Best Practice
Creative commons recommends the TASL approach:
T = Title (e.g. It is the beautiful Egypt)
A = Author (e.g. Karim Essm (with link to the author's page))
S = Source (e.g. It is the beautiful Egypt (with link to original Wikimedia Commons page))
L = License (e.g. Creative Commons Attribution-Share Alike 4.0 International (link to license deed))
See the complete example below.
More examples of TASL at the Creative Commons wiki here: https://wiki.creativecommons.org/wiki/best_practices_for_attribution
Databases sometimes provide their own attribution guidelines e.g. Freesound.