.env.development [best] -

By storing secrets (API keys, secrets, tokens) in a local .env.development file, you avoid committing sensitive credentials to version control (Git). If you accidentally push secrets to GitHub, you risk exposing them to the public. 2. Streamlined Developer Experience

In backend environments, all variables loaded from .env.development are attached directly to the global process.env object. You can access them anywhere in your backend code. javascript .env.development

| Problem | Solution | |---------|----------| | Variables are undefined | Ensure prefix (e.g., REACT_APP_ ) if using a frontend framework | | .env.development ignored in production | Check framework's env file loading rules – most ignore it when NODE_ENV=production | | Changes not applied | Restart the dev server | | dotenv overrides existing process.env | Use override: true (dotenv 16+) | By storing secrets (API keys, secrets, tokens) in a local

The cascading order of lookup priority typically flows from highest to lowest as follows: Streamlined Developer Experience In backend environments

PORT=3000 LOG_LEVEL=info

: It allows developers to define variables (like a local database URL or a mock API key) that are automatically loaded when running commands like npm run dev .