to share – to copy, distribute and transmit the work
to remix – to adapt the work
Under the following conditions:
attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
It is an anonymous work or pseudonymous work and 50 years have passed since the date of its publication (or creation, whatever date is the latest)
It is a photographic work, and 50 years have passed since the date of its creation
It is another kind of work, and 50 years have passed since the year of death of the author (or last surviving author)
It is one of "official texts of legislative, administrative or legal nature and their official translations"
Before July 5, 2009, a photographic work was protected for 25 years. Pictures created before July 5, 1984 have already been placed into the public domain.