Visual hierarchy operates through contrast — in size, weight, color, position, and space. The eye is drawn to difference; the greater the contrast between an element and its context, the higher its perceived importance. This is why headlines are large, why primary actions are coloured differently from secondary ones, and why white space around an element signals that it deserves attention.
Typography is the primary tool of hierarchy in most interfaces. The typographic scale — the relationship between display sizes, headings, subheadings, body, captions — is the backbone of visual order. A well-designed scale creates a clear reading path through even the most complex content.
Hierarchy is not decoration — it is information architecture made visible. Every layout decision about size, placement, and emphasis is a decision about what users should see, in what order, and with what level of attention. The designer who says "I want everything to be equal" is the designer who has abdicated responsibility for helping the user understand.