The migration file is a time capsule. It records, in unambiguous SQL, what the team believed about the world on a specific day. Read the migrations in order and you can reconstruct the history of a product almost more reliably than from the commit log.
This is why migrations should be written as if they will be read by strangers. Name them honestly. Comment the reasoning. Resist the urge to squash them into a clean origin story; the messiness is the evidence.
When you join a project, read the migrations before the code. The schema is the skeleton. The application is the soft tissue that grew around it.
