Packages

Every Go program is made up of packages.

You have probably noticed the package main at the top of all the programs you have been writing.

A package named "main" has an entry point at the main() function. A main package is compiled into an executable program.

A package by any other name is a "library package". Libraries have no entry point. Libraries simply export functionality that can be used by other packages. For example:

package main

import (
	"fmt"
	"math/rand"
)

func main() {
	fmt.Println("My favorite number is", rand.Intn(10))
}

This program is an executable. It is a "main" package and imports from the fmt and math/rand library packages.