What is 127.0.0.1?

127.0.0.1 is a special IP address called "localhost" or "loopback address." It is used to refer to oneself, that is, to the local computer.

When a program or service accesses 127.0.0.1, it actually connects to itself, bypassing the network. This is convenient for testing network applications without going online or to a local network.

Example in Go:

package main

import (
    "fmt"
    "net"
)

func main() {
    conn, err := net.Dial("tcp", "127.0.0.1:8080")
    if err != nil {
        fmt.Println("Connection error:", err)
        return
    }
    defer conn.Close()
    fmt.Println("Successfully connected to localhost")
}

This code attempts to connect to a local server on port 8080.