There are many sources of free ebooks and audiobooks. Most are public domain (no longer subject to copyright) but there are some places to find free original content.
These sources contain--or link to sources of--a range of media.
Hathi Trust - A digital library dedicated to the preservation of the culture record developed in partnership with research institutions.
Internet Archive - A digital library of text, music, video and more.
CC Search - Search for Creative Commons-licensed media including images, music and movies
Musopen provides recordings, sheet music, and textbooks to the public for free, without copyright restrictions.
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