Classic For Loop
In the case above, the value for number, is multiple by each iterator (i). Iterations will start at a value of 0 (i = 0), and will increase to 9. The 11th iteration (10) will be the end, and not executed. i++ signifies increasing the value of i by 1 each time.
For-Of Loop (Arrays)
Where i is the index of the array, each is printed out to the console.log in the example above
For-In Loop (Objects)
In the above statement, the loop returns all keys (k), and then outputs the value for each k (object[k])