Most people, to this day, prefer to convey files using email attachments rather than URLs. Over the years I’ve tried, and mostly failed, to explain why and how to use the URL-oriented approach. Programmers do this naturally, because programmers know the difference between transmission of data by value and transmission of data by reference. But almost nobody else does.

— John Udell: Why can’t Johnny download? (emphasis his. via Joe Grossberg)