The CSS box model is the structure of an element on a webpage. It consists of the element's content dimensions and expands around it including the element's padding, border, and margin.

Margin is the space between the element's border and another element's border/margin . Padding is the space between the element's border and the element's content.

The element height and width of an element are the height/width of the content plus whatever padding/margin has been applied. The border for an element is 0px by default, so this is typically not a factor.

This property is applying 25px of padding to the top and bottom and 50px of padding to the left and right since two values were given.

The border is the physical boundary of an HTML element. The outline is a way of making the border stand out but is not actually within the element's actual box model.