More about how loop [do while] works.

Hi Max. To start, the i += 1 is the same as saying i = i + 1 (and the same as i++ as Isaac mentioned above). So this just means that, with i (or x) as your starting variable set at 0 at the beginning, each time through the loop the i variable has 1 added to it. So after the first loop i = 1, after the second loop i = 2, and so on. Now, while loops and do while loops are very similar. The main difference is that a do while loop will always run at least once, whereas a while loop could run 0 times if its initial condition is not true. For example:

var i = 0;
while (  i < 0 ) {
  alert('This alert will not show.');
  i += 1;
}

This while loop will not run, because its condition starts out false. The variable i is set to equal 0 above it, and since 0 is not less than 0, the condition is false and the while loop will not run. However, consider the following do while loop:

var i = 0;
do {
  alert('This alert will show.');
  i += 1;
} while ( i < 0 )

Here, the alert will show once because the 'do' part is executed before the while condition is checked. It doesn't matter that i is never less than 0, the do part is run at least once either way. Finally, a for loop is just a quick way to write out a while or do while loop. For example:

for ( let i = 0; i < 10; i += 1) {
  alert('This alert will show 10 times.');
}

This above code allows us to do three things right away inside the parentheses after the word 'for': set a starting variable value for i, then give a condition saying that in this case the loop will run as long as i is less than 10, and then say that each time through the loop the value of i is increased by 1. It does the same thing but in less space. I really hope this helps!