How can a variable be designated as private in programming?

In Go (Golang), the access level to variables is determined by the case of the first letter of the name. If the variable name (or function, type, struct field) starts with an uppercase letter — it is exported (public), if with a lowercase — private (accessible only within the package).

Example:

package example

var PublicVar = 1   // public variable
var privateVar = 2   // private variable

func PublicFunc() {}  // public function
func privateFunc() {} // private function

Thus, to make a variable private, simply start its name with a lowercase letter.