What the Hell is 'Load Average' Anyway? A Guide to Actually Understanding System Load

Last Tuesday at 3:47 AM, my phone goes off. Alerts. Again. "Load average critical: 18.45 on prod-web-03" I grab my laptop, squinting at the screen, SSH in, run top. CPU usage: 23%. ...what? Look, if you've done DevOps for more than a month, you've be...