A citation is a reference to a published or unpublished source.
Reasons to cite your work is to:
There are two citation styles generally used in Computer Science research. These are ACM and IEEE styles.
A good reference guide to the ACM citation style is found on the Utica College website.
A good reference to creating in-text citations in the ACM citation style is on the ACM website:
Used with permission: http://research.library.gsu.edu/citationstyles
A good reference to the IEEE citation style is on the IEEE website.
This guide provides detailed examples of how to formulate IEEE citations and references.
Another good reference is on the Purdue OWL website.