Copyrights

"A Creative Commons (CC) license is one of several public copyright licenses that enable the free distribution of an otherwise copyrighted work. A CC license is used when an author wants to give people the right to share, use, and build upon a work that they have created" 

-Wikipedia 

The Licenses

Attribution 
CC BY

This license lets others distribute, remix, tweak, and build upon your work, even commercially, as long as they credit you for the original creation. This is the most accommodating of licenses offered. Recommended for maximum dissemination and use of licensed materials.

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Attribution-ShareAlike 
CC BY-SA

This license lets others remix, tweak, and build upon your work even for commercial purposes, as long as they credit you and license their new creations under the identical terms. This license is often compared to “copyleft” free and open source software licenses. All new works based on yours will carry the same license, so any derivatives will also allow commercial use. This is the license used by Wikipedia, and is recommended for materials that would benefit from incorporating content from Wikipedia and similarly licensed projects.

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Attribution-NoDerivs 
CC BY-ND

This license allows for redistribution, commercial and non-commercial, as long as it is passed along unchanged and in whole, with credit to you.

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Attribution-NonCommercial 
CC BY-NC

This license lets others remix, tweak, and build upon your work non-commercially, and although their new works must also acknowledge you and be non-commercial, they don’t have to license their derivative works on the same terms.

Attribution-NonCommercial-ShareAlike 
CC BY-NC-SA

This license lets others remix, tweak, and build upon your work non-commercially, as long as they credit you and license their new creations under the identical terms.

Attribution-NonCommercial-NoDerivs 
CC BY-NC-ND

This license is the most restrictive of our six main licenses, only allowing others to download your works and share them with others as long as they credit you, but they can’t change them in any way or use them commercially.

We also provide tools that work in the “all rights granted” space of the public domain. Our CC0 tool allows licensors to waive all rights and place a work in the public domain, and our Public Domain Mark allows any web user to “mark” a work as being in the public domain.

-Taken from CreativeCommons.org

(in US copyright law) the doctrine that brief excerpts of copyright material may, under certain circumstances, be quoted verbatim for purposes such as criticism, news reporting, teaching, and research, without the need for permission from or payment to the copyright holder.

"whether or not six seconds of the song in a user-generated video constitutes fair use is something for a court to decide"

-Wikipedia 

http://fairuse.stanford.edu/overview/fair-use/what-is-fair-use/

Royalty-free, or RF, refers to the right to use copyright material or intellectual property without the need to pay royalties or license fees for each use or per volume sold, or some time period of use or sales.

- WIkipedia

A royalty-free (RF) image license is much less restrictive than an RM license. A user typically pays a one-time fee for a royalty-free image license and can then use the image as many times and in as many places as he chooses. The "free" in royalty-free does not mean there is no cost for the license, but instead refers to being able to freely use the image without paying additional royalties. A small-business owner, for example, may opt to pay a one-time fee for RF images for his website.

- Smallbuissniness.chron.com