Language & WorldMental model
A language's most common word appears twice as often as the second.
Zipf's law: rank words by frequency and the n-th is about 1/n as common as the first. In the Brown Corpus of English, "the" is nearly 7% of all words, "of" just over 3.5%, then "and". Felix Auerbach found the same pattern in city sizes in 1913, though recent studies dispute that. Lesson: few words carry most of any text.
Useful: The 1,000 most frequent words of a language cover most everyday use; learn them first.
Source: en.wikipedia.org