Copyright protection laws for software were first adopted in the EU in 1991. By default, software available to the public is copyrighted by its original creator, who can then elect to assign a license for users to whom it is distributed. An ‘open source’ license, most types of which can be charged for, allows the user to view and modify the source code. Only open source software available without any restrictions on sublicensing is in the ‘public domain’. ‘Free and Open Source Software’ licences are open source though some hold restrictions. Some software is distributed under ‘proprietary’ licences, where users cannot redistribute or modify it, including most major operating systems - the first of which existed in the 1980s.