What does the default value mean for different data types?

In Go (Golang), the default value for variables is called zero value — it is the value that a variable takes if it is not explicitly initialized.

The main zero values for basic types:

• Numbers (int, float, etc.): 0
• bool: false
• string: empty string ""
• Pointers, slices, maps, interfaces, channels, functions: nil

For example:

var a int       // a == 0
var b bool      // b == false
var c string    // c == ""
var d *int      // d == nil

This helps avoid undefined variable states and simplifies initialization.