What are the six main Creative Commons licenses? — FAQ

All six modern licenses require attribution (BY). They differ in the additional conditions stacked on top:

CC BY — anyone may copy, remix, and reuse, including commercially, as long as they credit you.
CC BY-SA — same as BY, but derivative works must be licensed under the same terms (Share-Alike).
CC BY-ND — anyone may share the work, including commercially, but no derivatives are allowed.
CC BY-NC — non-commercial copy, remix, and reuse with credit.
CC BY-NC-SA — non-commercial only; derivatives must use the same license.
CC BY-NC-ND — the most restrictive: non-commercial sharing only, no derivatives.

Plus the public-domain tools: CC0 (waive all rights) and the Public Domain Mark (label works already in the public domain).