What are External CSS, Internal CSS and Inline CSS, which are the structural types of the CSS (Cascading Style Sheet) feature used to give an appearance to the HTML skeletal structure on websites, and in which situations they should or should not be used.
The External CSS structure is the file containing the CSS elements and classes with the .css extension and is linked to the HTML file with a link. They can be called from multiple pages in the Frond End design.
It is the CSS structure used with the classes defined between the <style></style> tags opened after the <head></head> tag, they can only be used on the page they are written on, they cannot be called from other pages.
Inline CSS structure is the style structure given directly to a specific tag in HTML. In this structure, CSS only works on the tag it is given, it cannot be called on other tags or affect other tags.
Google does not recommend this structure and says it should be avoided. It even states that CSP broke the content security policy.