Public Domain
A work enters the public domain when copyright expires or the original copyright holder relinquishes all their rights to the work.
It can therefore be used by anyone, for any purpose, without explicit permission or attribution.
Whether and when a work enters the public domain is dependent on its country of origin.
In the UK, copyright generally expires 70 years after the last surviving author dies.
Modifying a work in the public domain so that it is significantly transformed, creates a new copyright.
