> 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 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.


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