CSS stands for cascading style sheets and it is ultimately the language used to style the web page. CSS is a page of rules the HTML must follow because we tell it how we want it displayed on the screen. It controls the layout, the type font, the colors, etc.
CSS Selectors.
There are five categories of CSS selectors. Simple selectors which select the elements based on their name, id, or class. Combinator selectors are based on a specific relationship between the elements. Pseudo-class selectors are selected based on a certain state. Pseudo-elements selectors are able to select and style elements. Finally, attribute selectors are based on an attribute or its value.
CSS Syntax.
The selector speaks to the HTML element specifically needing to be styled. The declaration portion has properties and values separated by semicolons. These individual declarations include a CSS property followed by a colon and that is followed by the value. The entirety of the declaration block is enclosed by curly braces.