Config / Security

Environment variable

A configuration value kept outside your code so it can differ per environment and stay out of version control.

An environment variable is a setting written on a sticky note next to the machine rather than tattooed into the app — the code reads it at runtime via something like process.env.DATABASE_URL. This lets the same codebase point at a test database locally and the real one in production, and keeps secrets out of your source. AI loves to hardcode API keys directly into files; the fix is to move them into a .env file (which you add to .gitignore and never commit) and into your host's env settings for production.