Pseudo elements allow us to target elements that are not explicitly set in the DOM. Using ::before ::after we can actually create and manipulate elements in the DOM that do not impact the content. While ::first-letter ::first-line ::selection ::placeholder allow us to target elements that do not have a specific DOM element.

 About ‘blockquote‘:

blockquote { quotes: "“" "”" "‘" "’";}blockquote::before { content: open-quote;}blockquote::after { content: close-quote;}

About ::first-line, ::first-letter:

p::first-line { color: green;}p::first-letter { font-size: 2em; float: left; line-height: 1.7em; padding: 0 .3em; font-weight: bold;}