Visual Hierarchy
The deliberate ranking of elements by visual weight so the eye is guided through a composition in a specific order.
In practice
Visual hierarchy ranks every element by importance and makes that order visible through size, weight, color, position and space, so people read in the intended sequence. On a product page, the product name comes first, then the price, then the buy button, then the details. If everything is bold, nothing comes first. Designers test hierarchy by glancing at a layout for two seconds and noting what they remember.
Often confused with Emphasis
Visual hierarchy orders all elements from most to least important; emphasis singles out only the one dominant point at the top.
Try this
Style a plain-text event notice so a stranger reads the title, date, place and price in that order.