They are divided into two different types depending on where they attach to the root. The two types of affixes also differ in how they affect the meaning of the word. Prefixes modify the meaning of the root in some way. Often, they provide spatial information about an action named by the root. This is necessary to make a sensible English phrase.
English grammar requires that the verb is followed by a spatial preposition.
Suffixes have two functions, which we'll discuss in WebLecture 1.4. Their most important function is to indicate the part of speech of the word. They can change the word from one part of speech to another. In fact, multiple suffixes can be added to a single root, changing it first to one part of speech and then another. Because this use of suffixes is so important with Latin and Greek vocabulary, we'll spend some time discussing how to identify the different parts of speech.