Style Classes in HTML
Style classes are custom-built HTM tags. Each type of specifically formatted text is called a Style Class. A style class is a custom set of formatting specifications that can be applied to any passage of text in a web-page.
This is a SILLY heading based on the first definition of H1
This is a SERIOUS heading based on the second definition of H1
Thus it can be seen from above that a single style sheet can have multiple definitions for a single HTML tag. And thus one can even create one's own tags.
You can also place localised style class definitions within tags within your current tag definition such as P, SPAN or DIV
This text is green, but
this text is red.
Back to green again, but ...
... now the green is over, and we are back to the default color for this page.