There are many kinds of citation styles used in university writing, depending on the subject and that subject's national association guidelines.
For example, history uses the citation style called "Chicago". Most humanities courses use "MLA" from the Modern Language Association guidelines. Most social sciences (psychology, sociology, etc) use "APA" from the American Psychology Association guidelines. Other sciences like biology have their own style.
Why are there so many styles? Many publications and journals have been in existence for generations, which means standards have been set expert researchers know how to use them and can trust the way citations are written in their discipline.
There are many automatic citation generators found online (free or paid for) and also within library databases. They are marketed as an easy fix for inserting citations for papers.
However! "Automatic" may mean easy, but it's doesn't always mean "accurate" and they should be used with caution!
Always double-check your automatic citation to what the official citation source says, either on the official online citation site or Murphy Library's online citation guide.