A lot of these things are obvious just by looking. For example, "Slab serif typefaces are known for their distinct personality." Well, look at the two slab seri

A lot of these things are obvious just by looking. For example, "Slab serif typefaces are known for their distinct personality." Well, look at the two slab serif fonts in the example he gives you. You can see the letters have big exaggerated lines on the ends - the Ts have things coming off the top left and right and bottom center. These are the serifs and they are very large an decorative. His example has two fonts that have these serifs that are large and decorative and then the serifs for each are different. So it is kind of weird just looking at it. Oh, this T has a lot of decoration! But wait, that T over there has different decoration. It just feels weird on the eyes.