Later on, in Font Quality, you will learn that most of today's fonts don't offer different type styles. There's just the basic typeface.
All the prevalent DTP programs support making a font electronically italic etc. The font weight is easily changed on a computer, without the need of corresponding type styles.
This is all very handy, but the quality is by far not as good compared to a specially designed type style.
Type styles are classified based on the: