# Environment Variables Environment variables are key-value pairs set in the operating system or runtime environment that configure application behavior without hardcoding values in source code. They are used to store configuration such as database connection strings, API keys, feature flags, and service URLs. Environment variables follow the twelve-factor app methodology, which recommends strict separation of configuration from code. This allows the same application code to run in different environments (development, staging, production) with different configurations. Sensitive values like secrets and credentials should be stored as environment variables rather than committed to source control. In serverless platforms, environment variables are configured through the platform's interface or deployment configuration. Cloudflare Workers uses "secrets" and "vars" in the wrangler.toml configuration file. API gateways and serverless functions commonly use environment variables to store backend service URLs, authentication tokens for upstream services, and feature toggles that control routing or processing behavior. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.serverlessapigateway.com/glossary/e/environment-variables.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.