In Go, when variables are declared but not explicitly initialized, they are assigned their zero value according to their type. The zero value is a default value that depends on the data type. Here are the zero values for some common data types in Go:

• Numeric types (int, float64, etc.): 0
• Boolean type: false
• String type: ""
• Pointers, slices, maps, channels, functions, and interfaces: nil

Here is an example demonstrating zero values for various types:

package main

import "fmt"

func main() {
    // Numeric types
    var num int
    var floatNum float64
    fmt.Println("Integer zero value:", num)    // Output: 0
    fmt.Println("Float zero value:", floatNum) // Output: 0

    // Boolean type
    var boolean bool
    fmt.Println("Boolean zero value:", boolean) // Output: false

    // String type
    var str string
    fmt.Println("String zero value:", str) // Output: ""

    // Pointers, slices, maps, channels, functions, and interfaces
    var pointer *int
    var slice []int
    var mp map[string]int
    var ch chan int
    var fn func()
    var iface interface{}
    fmt.Println("Pointer zero value:", pointer) // Output: <nil>
    fmt.Println("Slice zero value:", slice)     // Output: []
    fmt.Println("Map zero value:", mp)          // Output: map[]
    fmt.Println("Channel zero value:", ch)      // Output: <nil>
    fmt.Println("Function zero value:", fn)     // Output: <nil>
    fmt.Println("Interface zero value:", iface) // Output: <nil>
}