Referencing is when you give acknowledgement to the sources you have used to write your assignment. 

You will use an in-text citation to show that you are referring to a source and this will often appear in brackets. 

For example:

It has been argued that case studies are a sound means of developing research theory (Eisenhardt and Graebner, 2007).

The reference gives full details of the source which has been cited to allow the reader to locate the source if they wanted to follow it up. 

For example:

Eisenhardt, K. M., and Graebner, M. E. (2007). Theory building from cases: Opportunities and challenges. Academy of Management Journal, 50(1), pp. 25–32.

Our Referencing pages have comprehensive guidance on how to reference different types of sources.