Last week the pilot light for my water heater went out. I tried to relight it by following the instructions pasted on the side of the heater, but they were as inscrutable as hieroglyphs. So I did what everyone does when they need to learn something: I went to YouTube. Bingo. Someone had posted a video showing how to relight my exact model. I crouched down near the heater, holding my phone at arm’s length so I could follow the instructions, as if I were peeking over an expert’s shoulder.

Get in-depth coverage of current and future trends in technology, and how they are shaping business, entertainment, communications, science, politics, and society.