> For the complete documentation index, see [llms.txt](https://docs.serverlessapigateway.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.serverlessapigateway.com/glossary/d/domain.md). # Domain A human-readable address used to identify a website or service on the internet. A domain (or domain name) is a human-readable address that identifies a resource on the internet, such as example.com. Domains are organized hierarchically: top-level domains (TLDs) like .com, .org, and .io sit at the top, followed by second-level domains and optional subdomains (e.g., api.example.com). Domain names are registered through domain registrars and mapped to IP addresses using the Domain Name System (DNS). Organizations typically configure DNS records to point their domains to web servers, CDN endpoints, or API gateways. Subdomains are commonly used to separate concerns, such as using api.example.com for API traffic and app.example.com for the web application. In API management, custom domains are important for branding and developer experience. An API gateway can serve multiple APIs under a single domain using path-based routing (e.g., example.com/v1/users) or serve different APIs on different subdomains. SSL/TLS certificates must be configured for each domain to ensure secure HTTPS communication. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.serverlessapigateway.com/glossary/d/domain.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. 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.