The citations and bibliography in any scholarly work have two purposes:
To do that, your citations and bibliography need to include complete and accurate information about your sources, arranged in a consistent way that does not confuse your reader. At this point in your research, you will all have encountered unhelpful footnotes with mysterious abbreviations, incorrect information, or other problems.
There are many ways to arrange the information. This is called "style" and there are several common styles in use. Commonly used styles in academic writing include The Chicago Manual of Style, MLA, and APA. Always check with your reader to find out if he/she cares about which style you use. When you write for publication, the publisher or journal editor will tell you which style they want you to use.
Why does it matter? Correct style will make things easier for your reader. And you want the reader to think about your ideas, not the messy punctuation at the bottom of the page.
You can decide on a citation style in a number of ways:
1. (Easiest/Most Important): What does your department/advisor/editor want you to use?
2. What is most common for your discipline:
3. What style is used in most of the works you are consulting?
An overview and summary of each style is found at Purdue OWL Research and Citation Resources
The full set of rules for each style is found in these publications:
These products allow you to store your references in a database, then automatically generate citations and bibliographies.
Zotero (see the library's Guide to using Zotero)
And there are others as well