CSS Pseudo-elements

::after

Used to insert some content after the content of an element.

::before

Used to insert some content before the content of an element.

::first-line

Used to add a special style to the first line of a text.

::first-letter

Used to add a special style to the first letter of a text.

::placeholder

Points to the placeholder of input elements in your presentation, mostly found in forms.

::selection

Matches the portion of an element that is selected by a user.