The simple absence of a copyright notice does not mean that a work is in the public domain. The general rules for determining whether a work is in the public domain are as follows:
- Works published on or before December 31, 1922 are in the public domain.
- Works published between January 1, 1923 and December 31, 1978, inclusive,
do not become public domain for 95 years from the date of publication,
so long as the there is a copyright notice and copyright owner also renewed the
- Works published after 1978 do not become public domain for 70 years from
the date the author dies (called, "life of the author" plus 70 years).
- "Freeware" software
- U.S. Government works
- Ideas, processes, methods, and systems described in copyrighted works