Final answer:
A prefix is the beginning of some words. It is a group of letters added to the beginning of a word to change its meaning or create a new word.
Step-by-step explanation:
A prefix is the beginning of some words. It is a group of letters added to the beginning of a word to change its meaning or create a new word. For example, in the word 'unhappy,' the prefix 'un-' changes the meaning of the word to 'not happy.'