In traditional typography, a font is a particular size, weight and style of a typeface. Each font was a matched set of metal type, one piece (called a “sort”) for each glyph, and a typeface comprised a range of fonts that shared an overall design.
Visual weight & direction
Every element on a web page exerts a visual force that attracts the eye of the viewer. The greater the force, the more the eye is attracted. These forces also appear to act on other elements, imparting a visual direction to their potential movement and suggesting where you should look next.