In 1935, Harvard linguist George Zipf pointed out that the frequency of the kth most frequent word in a language is roughly proportional to 1/k. This implies that the second most frequent word in a language has a frequency one-half that of the most frequent word, the third most frequent word has a frequency one-third that of the most frequent word, and so on. A distribution that follows this rule is said to obey Zipf's Law.