People who have the most power in society have historically determined what is proper language. In England the development of rules of grammar distinguished the upper classes from the lower classes. Grammar continues to distinguish classes in America today. No language has a standard form. Everyone speaks a dialect , a variation of a language spoken by a group of people.
Dialects are often regional.
Dialects do not indicate the speaker's intelligence. Spoken Language Differs From Written Language. Spoken language evolves much more quickly than written language. Spoken language is not inferior to written language. People in print-based cultures tend to be individually focused and linear in thinking.