What are mega menus and when should they be used?

Mega menus are large dropdown panels showing many navigation options at once - often with images, icons, and multi-column layouts. They're useful for complex sites with many product categories or services. E-commerce sites like Amazon use mega menus to display product hierarchies. Benefits include showing more options without multiple dropdowns, visual preview with images, and easier navigation of complex structures. However, mega menus are overkill for simple sites. They require careful design to avoid overwhelming users. Mobile mega menus need special consideration as they consume significant screen space. We implement mega menus for sites with 20+ pages across multiple categories. For smaller sites, simple dropdown menus or standard navigation work better.