Whenever you use someone else's words or ideas in your assignments, you must indicate that this information is belonged to another person by citing your source. This applies to written sources such as books, articles and web pages, as well as sources of other formats, such as images, sounds, film clips, or DVDs.
Citation is an important part in academic writing because:
It is an ethical practice;
It allows your reader to identify and locate the materials you have used in your work, so that they can find other relevant information on the topic;
It demonstrates that you have explored and read relevant materials when writing. This can also increase the credibility of your work;
It allows you to give proper credit for the ideas of others and avoid plagiarism.