The main package and main function define the entry point for a standalone Go executable program.
The main package is the entry point for a standalone Go executable, and the main function is where execution begins. Every Go program that runs as a binary must have exactly one main package containing a main function.
package main
func main() {
// Program execution starts here
}
Think of the main package as the front door of your house; it's the only place the outside world can enter to start your program. The main function is the specific room inside that door where the action begins. Without both of these, your Go code is just a library that other programs use, not a program that runs on its own.