What is the use of the z-index property in CSS?

The z-index property in CSS is utilized to control the stacking order of elements on a web page. This property enables you to specify which elements will appear on top when they overlap, allowing for effective layering of content.

When elements have a position property other than static (like relative, absolute, or fixed), the z-index can be applied to determine their positioning in the stacking context. Elements with a higher z-index value will be displayed above those with a lower value. This capability is particularly important in complex layouts where overlapping elements are common, such as modals, dropdowns, and image galleries.

Understanding how to manipulate the z-index is crucial for achieving the desired visual hierarchy in web design, ensuring that important elements are prominently placed and accessible to users.