# Configuration and time

This page covers the values your app reads from its environment, such as a
database address or an API key, and everything to do with time: the current
time, dates and time zones, and showing dates, times and other text to
people in their own language.

Two rules run through the page:

- **Your code never reads the environment or the system clock itself.**
  Settings arrive as typed `config.<field>` values, checked before the app
  starts. The time arrives as `clock.now`, which stays the same for the
  whole operation.
- **Values for machines and text for people never mix.** An `Instant` is
  stored and compared. A formatted date is only shown.