An information source is a source of information for somebody, i.e. anything that might inform a person about something or provide knowledge about it. Different types of questions require different sources of information. Information sources may be observations, people, speeches, documents, pictures, organizations, websites, etc. They may be primary sources, secondary sources, tertiary sources and so on.
“Information source.” Wikipedia. N.p.: Wikimedia Foundation, 8 Aug. 2015. 13 Apr. 2016.
<https://en.wikipedia.org/wiki/Information_source>.
