Why is ::selection categorized as a pseudoelement?

[Mo Green]

Hello together,

I am learning CSS as a beginner and i dont understand, why the pseudoelement ::selection is classified as a pseudoelement and not as a pseudoclass. I learned that a pseudoelement is by definition something, that separates a certain part of an existing element and styles this part with special instructions. But the selection-pseudoelement does not do this. It does not have to relate to a specific element, but can relate to every content the browseruser marks with the cursor. The content does not even have to be signed with markup to be selected by the ::selection-pseudoelement. 

Can anybody explain to me, why ::selection is categorized as pseudoelement? In my understanding it would fit much more into a dynamic pseudo-class, because it reacts to a userinteraction=the marking with the cursor. 

Thank you for answers and best regards,

Mo

Edited March 11, 2020 by Mo Green

[Ingolme]

It's a pseudo-element because a new element is created wrapped around the selected text. A pseudo-class is when a class is added to an existing element under certain circumstances.

[Mo Green]

Thank you for the answer. That makes it clear for me now. :)