A prefix is an addition that comes with a word. The prefix comes before the word, because pre- means before. For example, a prefix is the word pre-. Pre-school, pre-diabetes, preliminary. The prefix/suffix must have a root word to stick to. If you do a word like con, the word con means a fraud. But the root word is n, and n is only a letter. Words like co-pilot will be better. A suffix is a word that comes with the end of a root word. An example of a suffix is -ful. Wonderful, Teaspoonful, and grateful all have the suffix -ful.