Z-Index
Z-Index is a CSS property that controls the stacking order of elements on a webpage. It determines which elements appear on top of others when they overlap, essentially working along an imaginary Z-axis that runs perpendicular to the screen. By assigning different z-index values to elements, web designers can create complex, layered visual effects, ensuring that critical content, such as navigation menus or modal windows, remains accessible and visible above other page content.