Developers know that good code contains meaningful comments that document their choices and unusual situations. You just preface the text with an apostrophe character (‘), so that VBA ignores the line. Later, you —  or other developers who maintain the database — can quickly peruse the comments instead of interpreting code.
You can also share comments about the design of an Access form, report, or control with other developers using hidden controls. It’s an innovative albeit nontraditional use for controls — usually, a label control. By setting such a control’s Visible property to No, the control is visible only in Design view. When you or another developer opens the form in Design view, there are your comments. This type of commenting is especially helpful when the object requires no module, which is where you store more traditional commenting.