What kind of box is the default type for the box-sizing property?

The default type for the box-sizing property in CSS is content-box. This means that the width and height of an element are defined by the content alone, excluding padding and borders. As a result, when you set width and height, they apply to the content area, and any padding or border will increase the total size of the element. To include padding and borders in the total size, you can use box-sizing: border-box.