Not all digital content is free to use (no, not even everything in Google Images is free).
If you are publishing your work online, consider the following to be sure you are using, adapting, and citing content and materials appropriately.
1. Use media with stated licenses.
This includes Creative Commons and Public Domain; these works will be clearly labeled so that you understand what you need to do to edit or reuse them. This does not take away the need for giving credit where credit is due. Attribution is part of Creative Commons and items will typically state this.
2. See if your situation qualifies as Fair Use.
If you are using these materials in the classroom, as a student or instructor, your work may be subject to different guidelines. Remember, you will still need to provide citation information to give proper credit to your sources. When considering Fair Use, think about the academic use of what you are doing.
3. Create your own media.
Thanks to technology, creating your own images and media is easier than ever before. Use online graphic creators (canva, visme, etc), a camera, audio, or video recorder to make your own media.
4. Ask for permission
See if you can find the contact info for the creator of the work. Sometimes you can simply get permission to re-use the work.
In order to use audio, video or images, you should have a basic understanding of the terminology many of the sites use with regards to usages and rights. These are a few terms that are important to be familiar with when dealing with content.
Definitions adapted from: Black's Law Dictionary, 8th Ed., Edited by Bryan A. Garner, published by Thomson West (1999) & Creative Commons (http://creativecommons.org) and copyright.gov
The boxes below list links to places to search for Creative Commons and Public Domain materials that are easy and safe to use and adapt in your own work.
Google Advanced Image Search (click tools -> usage rights -> labeled for reuse or noncommercial reuse)
NYPL Digital Gallery (Some of the images in the Digital Gallery may be subject to third party rights such as copyright and/or rights of privacy/publicity)
Artifact and Analysis (Smithsonian)
Everystockphoto - Search engine for free images.
Image*After - Database of images and textures.
Open Clip Art - Lots of free clip art.
Pics 4 Learning - Free copyright friendly images for educational use.
Stockvault - Over 60,000 images to browse and download.
Yale Digital Commons - Digital assets curated by Yale University.
ccMixter - Thousands of free sounds and music to download and use.
Piano Society - Classical piano music uploaded by users that is free to use.
YouTube Audio Library - Download background music for your video, completely free.
Jamendo - An independent music community with unlimited free streaming and downloading.
Free Music Archive - Many genres available as well as curated sounds to help you find what you need.
Melody Loops - Royalty free background music.
SoundBible - Free sound clips, sound bites and sound effects.
JamStudio - Create your own music online and download it. Registration required.
Opsound - Independent musicians with free music to use.
Audionautix by Jason Shaw - Original, electronic songs that are free to use.
Netlabels - Part of the Internet Archive. The collection is completely free with catalogs of virtual record labels.
Partners in Rhyme - Some pay and some free content. Also has effects, Midi and loops to use.
Moby Gratis - Created by the artist, Moby, Online application system, which registers you to use the site.
Incompetech - Background music to download by Kevin MacLeod.
Sound Search Engine - Huge site for finding sound effects.
Classic Cat - Find classical music for video soundtracks.
Purple Planet - Lots of free full length songs to download and use.
Zap Splat - Free sound effects with a huge variety to choose from.
PD Sounds - Public Domain sound library.
Cylinder Preservation and Digitization Project - Mostly Public Domain songs from before 1924 that have been digitized .
Soungle - Royalty free sound effect search engine.
Freesound.org - Samples and search engine with a forum for discussions.