A primary source is an account by an eyewitness or the first recorder of an event - or documents produced at the time an event occurred. Diaries, paintings, interviews, memoirs, official records, original works, relics, speeches, original scientific study.

A secondary source analyzes or discusses a primary resource. Journal articles, books, newspaper articles, textbooks, articles that decipher a scientific study, an article about a relic or piece of artwork.

Primary scientific articles are written by the researchers themselves to describe original research work that they have completed. These articles will contain high-level vocabulary and present original data, often displayed in tables and charts.

Secondary scientfic sources will mention the original study and then attempt to explain the findings in non-technical terminology. These will often be written by people outside of the research profession.