Reusing works that have a Creative Commons license ALWAYS requires attribution. Learn how to attribute CC-licensed works by following these best practices -- or use a browser plug in such as OpenAttribute to help you.
The most common forms of attribution include the three elements, two of which are hyperlinked:
(c) Author Name "Name of work [hyperlinked to where you found the work]" License [hyperlinked to license]
License terms on some sites (this one is from Flickr.com) may appear as Creative Commons icons or appear when a hyperlink is moused over.