1) In the CSS, a class selector is a name introduced before by a full stop (“.”) and an ID selector is a name introduced before by a hash character (“#”).
2) The distinction between an ID and a class is that an ID distinguishes and sets style to one and just a single event of an element while a class can be appended to any number of elements.
3) You can also characterize your own selectors as class and ID selectors.
4) The advantage of this is you can have a similar HTML element, yet present it diversely relying upon its class or ID.