What is the difference between classes and IDs in CSS? Explain with example of where to use [duplicate]

Answer 1

Short and simple:

Classes may be used as many times as needed (and are defined by a period). Ids can only be used on ONE element (and are defined by a pound).

I am a class

Look at me, also a class

I am special, you can only have one of me or I do not meet XHTML standards