From Serverless Applications with Node.js by Slobodan Stojanović and Aleksandar Simović
To understand serverless, consider for a moment washing machines. This might sound like a crazy place to start, but owning a server nowadays is similar to owning a washing machine. Everybody needs to clean their clothes, and the most logical solution seems to be buying a washing machine. But most of the time the washing machine is plugged in, it’s doing nothing. At best, it’s used five to fifteen hours per week. Same goes with servers. Most of the time, your average application server is waiting to receive a request, doing nothing.