Analogies

Sometimes analogies help to explain this to people new to the area.

Minefield

Richard Stallman has frequently mentioned this analogy in parts of his speeches:

• http://www.gnu.org/philosophy/stallman-mec-india.html
• http://www.gnu.org/philosophy/fighting-software-patents.html
• http://www.ifso.ie/documents/rms-2004-05-24.html

Literary patents

Again citing Richard Stallman:

• http://www.gnu.org/philosophy/software-literary-patents.html