Primary source and secondary sources are the two types of resources for information that are used in research.
Primary source refers to any kind of document or speech which is created or produced during the time of research study. It offers an insight into a particular event. It includes Autobiographies, diaries, interviews, letters, raw research data, speeches, photographs etc.
On the other hand, Secondary sources actually provide interpretation or analysis of the primary sources. They are at a remote site from the original event or incident. It includes encyclopedias, Biographys, Literary criticism etc.