How it Works: Our brains seek patterns, so when we see objects that are similar, we instinctively link them together in our perception, even if they are not close to each other.

In Design: This principle is widely used in branding, where color and typography are consistent across different touchpoints to create a sense of unity. Similarly, icons with the same shape or color scheme in an app or website guide users toward understanding their shared functionality.

Example: Think of a set of buttons on a website. If all the buttons that perform similar actions are the same color or shape, users will associate them with the same function.