A namespace is a context, within which the names are unique. Namespaces can be hierarchical, meaning the names within each hierarchical level are unique. Example:
- Football: Namespace is the team. The shirt number is the unique name within this.
- Telephony: Namespace is the dialing code. The connecting number is the unique name within this.
- Domain name system (DNS): Namespace is a second-level domain. Here, the hostnames (www) and the subdomains (dev) are unique.
- URIs (Uniform Resource Identifiers): Each URI can be regarded as name with the superordinate resource as the namespace.