A prefix is a group of letters added to the beginning of a word to change its meaning, while a suffix is a group of letters added to the end of a word for the same purpose. These are called affixes, and they modify the root word's meaning or function without standing alone as independent words.
Prefixes appear before the root word. Common examples include "un-" (unhappy, unclear), "re-" (redo, rewrite), "pre-" (preview, preheat), and "dis-" (disagree, dislike). Each prefix carries its own meaning—"un-" typically means "not," while "re-" means "again."
Suffixes appear after the root word. Examples include "-ful" (helpful, careful), "-less" (hopeless, careless), "-ing" (running, singing), and "-ed" (walked, talked). Suffixes often change a word's part of speech: "-ing" can turn a verb into a noun or adjective, while "-ed" typically marks past tense in verbs.
Understanding prefixes and suffixes helps readers decode unfamiliar words by breaking them into recognizable parts. For instance, "unhelpful" combines the prefix "un-" with the root "help" and the suffix "-ful," so its meaning becomes apparent even if you've never seen the exact word before. Learning common affixes is therefore a powerful vocabulary-building strategy.