Presenting Mathematical Concepts on the World Wide Web
Intellectual Property Rights ... and Wrongs

The original date of the work:

• prior to 1909,
• between 1909 and 1977,
• between 1978 and 1988, or
• since 1989;

Whether it was the work of:

• a single author,
• an entity (such as a business),
• a mixture of people and entities (and how many of each),

Whether the author(s) are:

• US citizens or residents,
• citizens or residents of signatories of the Berne Convention, the Universal Copyright Convention,

And so on.

At various points in the past, the duration rules were different. The rules that apply to any given piece of intellectual property are those that were in effect at the time the copyright went into effect, so the duration of older works will not be exactly the same as it is for works created now.

In general, however, the idea has been to encourage development of new work by giving this mini-monopoly on intellectual property to authors for their own lifetimes, and to let authors pass it on to their immediate heirs, but not to have it last for many generations to come.