return VS yield

Most of programming language, functions normally hands over the value using return keyword. But using yield keyword can bring the value very different way.

The first noticeable difference is that when using the return keyword, the result value is provided only once, and the yield keyword provides the result value divided by multiple times.

using System;
using System.Collections.Generic;

class Program
{
static IEnumerable GetNumber()
{
yield return 10;
yield return 20;
yield return 30;
}

static void Main(string[] args)
{
foreach (int num in GetNumber())
{
Console.WriteLine(num);
}
}
}