How to distinguish "affect" from "effect" can be difficult even for highly educated English speakers, and the usage error pops up time and time again on résumés, Leavy-Detrick told Business Insider.
Simply put, "affect" is almost always used as a verb, as in, "The weather affected my plans." Meanwhile, "effect" is generally used as a noun, as in, "The diet pills did not have an effect."
Not surprisngly, the two words are among the most looked-up words in the dictionary.