localhost

localhost is a reserved hostname that points back to the computer you are using. It resolves to the loopback address 127.0.0.1 (IPv4) or ::1 (IPv6), so traffic never leaves the machine.

Why it matters

Developers run web servers and databases on localhost to build and test before deploying. It also explains confusing situations: a service bound only to localhost cannot be reached from other machines, and a monitoring tool cannot check your localhost:3000 from the internet.

Example

$ npm start
Server listening on http://localhost:3000

Opening that address works on your computer. A friend entering your public IP cannot reach it unless the server listens on all interfaces and the port is exposed.

Common mistakes

• Giving a localhost URL to a webhook provider or monitor; it points to their machine, not yours.
• Binding a database to 0.0.0.0 instead of localhost and exposing it publicly.
• Mixing up localhost and your machine's network IP.

Related

• IP address
• IPv4
• IPv6
• Web server
• टूल: Port checker

यह पेज सामान्य जानकारी है, जिसे हमारी संपादकीय टीम ने लिखा है और दस्तावेज़ीकरण बदलने पर अपडेट किया जाता है। सर्वर और प्रदाता अलग-अलग होते हैं, इसलिए बदलाव पहले सुरक्षित तरीके से जाँचें। देखें: संपादकीय नीति और अस्वीकरण.