What's the difference between an id and a class?

Answer 1

When applying CSS, apply it to a class and try to avoid as much as you can to an id. The ID should only be used in JavaScript to fetch the element or for any event binding.

Classes should be used to apply CSS.

Sometimes you do have to use classes for event binding. In such cases, try to avoid classes which are being used for applying CSS and rather add new classes which doesn't have corresponding CSS. This will come to help when you need to change the CSS for any class or change the CSS class name all together for any element.