The second-biggest city is about half the size of the biggest, the third about a third

Rank every city in a country by population, or every word in a language by how often it's used, and a strange pattern appears: the top-ranked item is roughly twice as big as the second, three times the third, and so on. Linguist George Zipf popularised the pattern for word frequency in 1932, though the same regularity had already been spotted in city sizes decades earlier. Nobody fully agrees why it appears in cities, languages and incomes alike, but it shows up with eerie consistency.

— George Kingsley Zipf, Zipf's law — The Psycho-Biology of Language, 1935