Material Design is based on the idea of translating the physical properties of real-world materials into the virtual screen, and it takes much of its inspiration from paper, ink, and print techniques.
Material Design encourages designers and developers to create on-screen objects that seem to possess the same qualities as real-world objects. This means using techniques such as shadows, light, and elevation to create a sense of depth and edges.
The way Material Design objects move also mimics how objects move in the physical world; for example, two real-world objects cannot occupy the same space simultaneously or pass through one another, so your on-screen objects shouldn't either.
To help you create this illusion, Material Design introduces the concept of a simulated 3D space where all UI objects possess X, Y, and Z coordinates. The Z coordinate is particularly important, as the positive Z axis extends outward toward the user, creating that sense of depth that's so...