Topic summary
Boldface

Extracted from the Wikipedia article Emphasis (typography).
Design
There are many designs. With both italics and boldface, the emphasis is correctly achieved by swapping into a different font of the same family; for example by replacing body text in Arial with its bold or italic style. Professional typographic systems, including most modern computers, would therefore not simply tilt letters to the right to achieve italics (that is instead referred to as slanting or oblique), print them twice or darker for boldface, or scale majuscules to the height of middle-chamber minuscules (like x and o) for small-caps, but instead use entirely different typefaces that achieve the effect. The letter 'w', for example, looks quite different in italic compared to upright.