When you are researching assignments and noting the details of information sources you have used, you are creating the basis of a reference list.
Why cite and reference?
It enables the reader to follow up on the original work if desired;
It is an academic requirement that credit be given to the original author for their own ideas and work and in fact, It is also an infringement of copyright laws not to provide proper citations and referencing. See Module 6 Plagiarism;
Citing authoritative sources, validates a statement or argument.