CSS selectors are used to "find" (or select) the HTML elements you want to style.
We can divide CSS selectors into five categories:
Simple selectors (select elements based on name, id & class)
Combinator selectors (select elements based on a specific relationship between them)
Pseudo-class selectors (select elements based on a certain state)
Pseudo-elements selectors (select and style a part of an element)
Attribute selectors (select elements based on an attribute or attribute value)