An open source analogy: Open source is like sharing a recipe
I love listening to open source gurus explain open source to those who have never encountered it, and especially to those with little computing background. In conversations with folks who may have never heard the term 'source code,' open source advocates don't typically have recourse to related words like 'Linux,' 'copyleft,' or 'binary blobs.' That comfortable vocabulary suddenly fails them, leaving them frustrated and stammering.
I've observed some artful feats of analogy by open source zealots eager to help others understand the open source way. Some of these analogies are brief; others are elaborate anecdotes. But all are creative attempts to demonstrate similarities between open source and something an audience finds more familiar.
I have my own open source analogy, one that has lead (I'm happy to report) to a satisfying number of wide-eyed 'Ah-ha's!' Here it is: