The plain-English version
A special hostname that resolves to a loopback address in the current network environment. In a container or remote environment, it may refer to that environment rather than your physical computer.
Why it matters
A local app address usually is not a shareable public address.
The docs behind it
- MDN — local testing servers
- IETF RFC 6761 — localhost resolves to loopback
- Docker — container networking and loopback interfaces
Documentation links checked .
Editorial review · October 28, 2026
Corrected: Adds the loopback/network-environment distinction relevant to containers and remote development.