The document discusses prefixes and suffixes. Prefixes are added to the beginning of root words to change their meaning, with examples like re- and un-. Common prefixes include re-, hyper-, un-, tri-, pre-, mis-, and sub-. Suffixes are added to the end of words, with examples of adjective suffixes like -ful, -y, -ing, and -ed and noun suffixes like -or, -th, -ine, and -er. Prefixes and suffixes can modify a word's meaning, part of speech, or tense.