Pseudo Classes - (:)
specifies a special state of an element
:not, :active, :focus, :hover, :matches, :any-link
:(first, nth, last)-child, :nth-last-child
:(first, nth, last)-of-type, :nth-last-of-type
Pseudo Elements - (::)
specifies a specific part of an element
::before, ::after, ::selection, ::first-letter, ::first-line