define harvard referencing

Harvard referencing is the most commonly used referencing system at UniSA. The UniSA Harvard style , which is outlined in the Harvard referencing guide UniSA, is derived from guidelines established in Snooks & Co (eds) 2002, Style manual for authors, editors and printers, 6th edn, Wiley & Sons, Australia.
There are two important components to Harvard referencing.

Although there seems to be some ambiguity as to the exact origin of what is now referred to as the Harvard style of referencing, an article in the British Medical Journal sheds some light on the issue:
Harvard is a parenthetical author-date reference system. Harvard reference style originates from Harvard University, where a professor of zoology in the 1880s first used parenthetical references.

Other styles that are used at Reading include Harvard, Oxford, APA, Chicago and Vancouver (numeric).
Remember that if you are studying modules in different departments or schools, they may each prefer a different referencing style.

References:

http://awelu.srv.lu.se/sources-and-referencing/quick-guides-to-reference-styles/harvard/
http://libguides.reading.ac.uk/citing-references/referencingstyles
http://apastyle.apa.org/learn/faqs/web-page-no-author