Failing to reference appropriately could result in your assessors thinking you are guilty of plagiarism. Plagiarism is presenting someone else's work or ideas as your own, with or without their consent, by incorporating it into your work without full acknowledgement

What is plagiarism?

In all aspects of academic study and research, thoughts and ideas inevitably build on those of other writers or researchers - this is a legitimate and indeed essential part of the academic process.  In an academic context, plagiarism implies a deliberate act on the part of the writer or researcher to use the work, ideas or expressions of others as if they were his or her own.

You may plagiarize other's people work when:

• you fail to acknowledge fully the sources of knowledge and ideas that you use in your work;
• you incorporate the words of others into your writing as if they were your own;
• you 'string together' ideas or facts taken from others without presenting your own viewpoint

It applies equally to published text and data drawn from books and journals, and to  unpublished text and data, whether from lectures, theses or other students'  essays. You must also attribute text, data, or other resources downloaded from websites.
 

Fully reference and acknowledge the work of others

 
Make sure that when you are reading or researching for any written work or presentation, you include in your notes, or on any photocopies, the full reference details of teach source that you use.
 

Use your own words and develop your own writing style

 
At first it may seem very difficult to develop your own views, and you will probably find yourself paraphrasing the writings of others as you attempt to understand and assimilate their arguments. However it is important that you learn to develop your own voice. You are not necessarily expected to become an original thinker, but you are expected to be an independent one - by learning to assess critically the work of others, weigh up differing arguments and draw your own conclusions.
(University of Oxford)