OER is defined by the William and Flora Hewlett Foundation as "teaching, learning, and research resources that reside in the public domain or have been released under an intellectual property license that permits their free use and re-purposing by others.
Looking for historic art to be used in your project? The J. Paul Getty Museum has thousands of artworks that are free to openly use with their Open Content Program. Images under this category are in the Public Domain, but make sure that Open Content Images is checked in the search bar.
The NYPL has digitized a large collection of their media and has made them available to download. This link will filter only the items that are in Public Domain, but check the Rights Statement at the bottom of the image page to be sure.
Looking to add music freely to a project? Dig CC Mixter hosts a large collection of free-to-use music. Be sure to check if you need to credit the artist before use.
Exactly as it sounds, Free Music Archive has a large collection of open licensed audio. Be sure to check the Creative Commons license before downloading media.
