Why is it important to include citations in a research paper report?

Proper citing and referencing give your work a (potentially) public quality. Anyone with some knowledge of the subject can check (verify) your work. For example, they can see whether you have really understood your sources, whether you have quoted out of context or intelligently - and so on.

It is also important because if you get info from a source and use it in the paper it can be considered as plagiarism even if you change the Words around. But if you cite the source and author when you use the information it will not be considered plagiarism