Let's tackle the difference between class and ID selectors in CSS - a question that frequently stumps even seasoned developers. A class selector targets elements that share the same class attribute. You can use a class on multiple HTML elements, and multiple classes can be used on a single element. It's denoted by a period ('.'). An ID selector, on the other hand, is used to select one unique element. Each page can only use an ID once, and each element can only have one ID. It's represented by a hashtag ('#').