All of the sites below provide images that are free to use in projects. Be sure to still check the permissions for any limits on use.
Public Domain Images:
High-quality public domain photos.
Images on Flickr in the public domain. No copyright restrictions.
Public domain digital repository.
HD image repository in multiple categories.
Images from the National Aeronautics and Space Administration
Images from the National Oceanic & Atmospheric Administration. You are asked to credit NOAA if you use their images.
Creative Commons Images
Download Creative Commons images with the attribution already attached. Easy!
Creative Commons images on Flickr
CC-licensed images. Includes attribution and embed code to easily allow you to include in online projects and blogs.
AUDIO
Public Domain Audio
A collection of historical American music for learner/educator use.
VIDEO
Public Domain Video
This archive, part of the Internet Archive, features 100's of movies and videos in the public domain. Free to use and share.
Every video in this section of Vimeo is in the public domain and free to use.
Creative Commons Video
Video clips from the internet archive that are designed to be used in other videos. Videos are submitted with different Creative Commons licenses. Be sure to check the license type before using.
Portion of the Internet Archive featuring movies, videos, and news uploaded by Creative Commons and Public Domain content ranging from classic full-length films, to daily alternative news broadcasts, to cartoons and concerts.
Section of Vimeo featuring only Creative Commons-licensed video. Check license for what you can do with the footage and how to provide attribution.