sociolinguistics
Sociolinguistics is the combined study of sociology and linguistics. It takes a look at how society affects the way that we use language and how society itself affects language. The pioneer of Sociolinguistics in the West was William Labov, who conducted many studies, observations, and experiments to see how people talk.
Sociolinguistics deals with the different social factors that affect different communities and the way that they speak. These communities differ in social class, race, gender, and region. The fact that there are dialects and vernaculars shows that society affects our language. In fact, it's as easy as comparing how you speak to your friends, to how you speak to your family, to how you speak at your job. Each of those areas affects your language and mannerisms in a different way. I'm going to guess that your language is far more casual and relaxed when you're speaking to your friends than the language that you use when you're at work!
A fun example of Sociolinguistics is the different slang that younger generations use than older generations. You rarely see the words "radical" and "heavy" anymore, but you do see words like "fam," "doggo," and "smol." The invention and wide-spread access of the internet has had a huge impact on our language and the way we use it and has especially impacted the slang words that we use - they now spread at a much faster rate than they used to!