A primary source refers to documentation or material presented by parties that were directly present or involved in the referred subject, while a secondary source refers to documentation derived from the opinion or views of primary sources. Primary sources are typically able to provide an inside view of an event because they were physically present. An example of a primary source would be Neil Armstrong describing his experience on visiting the moon.
Another key difference between primary and secondary sources is that while primary sources provide direct account, secondary sources describe, interpret, analyze, summarize and evaluate the views offered by primary sources. Good examples of secondary sources include opinions offered in newspaper articles, movie or book reviews and biographies. Primary sources may refer to creative work, such as novels, music, art and poetry. It may also refer to original documents such as speeches, manuscripts, interviews, news film footage, autobiographies and diaries.
In addition to primary and secondary sources, there is a third type of source: tertiary sources. Tertiary sources refer to information that contains a mix of both primary and secondary sources. Some examples include encyclopedias, textbooks, dictionary, guides and fact books. To put all three sources in perspective, The Diary of Anne Frank" is a primary source, a monograph or publication that exposits the diary would be classified a secondary source and an encyclopedia on the Second World War would be a tertiary source.