Do I need to include italic fonts?

Question

HTML

Hello.
When connecting google fonts fonts, you can choose to connect with the italic style, why is this needed? After all, if I do not connect these styles and use font-style: italic, the font will still be italic.
So why then connect them?
Thank you.
Example:
fonts.googleapis.com/css?family=Roboto:400, 400i
Or
fonts.googleapis.com/css?family=Roboto:400

font-family: 'Roboto', sans-serif;
font-style: italic:

Answer 1

Then, if the text is italic or bold, and the font does not have such a style, then the browser will draw them itself, making pseudo-styles (~faux bold, ~slanted). And in this case, some fonts may be crooked, dirty or blurry.