Form obeys function. This slogan emphasizes the core principle of functionalism, that is, the form of design and architecture should be directly influenced by its function and purpose, and the design and architecture should meet the requirements of its purpose and function, and the form and appearance are produced in order to better realize these functions. This slogan was widely spread and applied in the modernist architectural movement in the early 20th century, which had a far-reaching impact on later design and architectural ideas.