You can use Material Design for your own products too — Google publishes extensive, openly available documentation for it.
What Material Design covers
Material Design is a full system, not just a style. It defines foundational guidelines for colour, typography, spacing, elevation (the shadows that imply depth), and motion, alongside a large library of ready-made components such as buttons, cards, floating action buttons, dialogs, and navigation patterns. The latest version, Material 3 (“Material You”), adds dynamic theming that adapts colour to a user’s wallpaper and preferences.
Why designers use it
Because it is consistent, well-documented, and accessible by default, Material Design lets teams move quickly: designers reach for proven components instead of reinventing them, and developers have a clear, shared design system to build against. That shared language is especially valuable for responsive products that need to feel coherent across phones, tablets, and the web.