The initial value of a CSS property is its default value, as listed in its definition table in the specification. The usage of the initial value depends on whether a property is inherited or not:

• For inherited properties, the initial value is used on the root element only, as long as no specified value is supplied.
• For non-inherited properties, the initial value is used on all elements, as long as no specified value is supplied.

You can explicitly specify the initial value by using the initial keyword.