Help in constructing citations in the different styles can be found at our Citing Sources page, but why are there so many anyway? Different citation styles have evolved over time to meet the needs of the different disciplines. All use similar elements, but there may be more emphasis on different formats in the different styles. So humanities styles may have clear directions on how to cite correspondence, while science styles could provide more coverage on how to cite datasets.
There are reasons why these styles are entrenched.
In any case, as a student creating citations it is valuable to ASK your teacher:
Well, actually, there are dozens and you will only likely need to know a few. The main styles which are used by many different disciplines are:
Other styles may be quite unique to the discipline (ACS - American Chemical Society), or variations on one of the above three (ASA - American Sociological Association).
Remember, to get help constructing citations in the different styles, use our Citing Sources page.