What is Follow the sun?

Follow the sun is an on-call model where responsibility moves between teams in different timezones so that whoever is on call is always in their working day, and nobody is paged at night.

It needs people in at least two, usually three, regions roughly eight hours apart, for example Europe, the Americas and Asia-Pacific. Each region has its own roster; the schedule hands over at fixed local times, with an overlap for briefing.

The failure mode is a region with only one person: a single holiday breaks the chain, so each region needs its own minimum of two to three people.