The prefix is the beginning part of a word (for example, the “un” in ungrateful). The root word is the original state of a word that can grow longer with prefixes and suffixes (for example, “play” in Replay). A suffix is a part at the end of a word (like “ful” in ungrateful). These word stems/parts of words have different meanings that can sometimes help determine a meaning of a word. Some words may not have all parts (prefix, root, suffix), though. These are words like “preschool” (prefix: pre and root word: school) and younger (root word: young and suffix: er). I hope this helps you out! Good luck :)