These two words differ in spelling by one letter: one means to influence, the other means to cause. What are the two words?

It's a classic case of verbal confusion, where a single vowel swap creates a world of difference in meaning. The two words are often mixed up because they sound so similar, yet they play distinct roles in a sentence. Generally, "affect" is the action word, a verb that means to influence or produce a change in something. For instance, you could say that rainy weather *affects* your mood. On the other hand, "effect" is most commonly used as a noun to describe the result or consequence of that change. So, the *effect* of the rain on your mood might be a feeling of coziness.

The shared history of these words helps to explain their similarity. Both trace their origins back to Latin through French. "Affect" comes from the Latin word *afficere*, which means "to act on" or "to do something to." This origin neatly aligns with its modern use as a word of influence. "Effect" comes from the Latin *efficere*, meaning "to bring about" or "accomplish," which connects directly to its role as the outcome or result of an action.

To make matters more interesting, both words have less common secondary meanings. "Effect" can be used as a verb meaning to bring something about, such as to *effect change* in policy. "Affect" can also be used as a noun in psychology to describe an emotional response or demeanor. A simple way to remember the most common usage is the mnemonic device RAVEN: Remember, Affect is a Verb, Effect is a Noun.