The website, Vocabulary.com, tests your knowledge of common and not-so-common words in the English language. Here you are presented with multiple-choice questions on over 40,000 words. If you miss an answer, the website offers simple explanations about the origin and history of the word. This website includes a free dictionary, explains the difference between similar-sounding-yet-not-to-be-confused words (for example: accept/except, stationary/stationery, principal/principle, etc.), and a place for you to create your own vocabulary lists.
