As you research independently, you may come across types of information and sources that you might not have seen before, or find difficult to identify. This can be particularly true when you find something online, as the type of source it is might not always be obvious.
It is also more likely to be the case in certain disciplines:
Whatever the source, in order to include the correct information in your final reference, it is important to identify the type of source you have found. You will soon become familiar with the more conventional sources in your subject, but it is worth being aware that different types will have, sometimes subtly, different forms.
You can make sure you have got this correct by checking back against the guide to your referencing style, if you are ever in doubt.