This page explains citation styles, which are designed to serve different audiences, for example general readers or historians or biologists or engineers.
Quick recap: Source Type is primary, secondary, etc; Source Format is book, article, etc; Citation Style is medical, engineering, etc.
Plagiarism is using other peoples' work or idea without giving them credit. Plagiarism is a kind of dishonesty, and can lead to failing an assignment, failing a class, or getting expelled from college.
Avoid plagiarism by keeping track of where you are getting your ideas. When you find sources, make a sources list right away. Take notes from one source at a time. Try to put ideas in your own words; avoid copying and pasting text. If you must reuse someone else's words, put them into quotation format and state exactly where they came from.
If you don't cite sources correctly, you will omit essential information and commit plagiarism. Standard citation styles for the bibliography and references include: Modern Language Association (MLA), American Psychological Association (APA), Chicago, and American Medical Association. Your professor will tell you which style to use, and these resources show you how: