Primary Sources are:

• direct or firsthand evidence about an event, object, person, or created work
• historical and legal documents, including maps, official statements, treaties, and laws
• newspaper articles
• eyewitness accounts
• personal written accounts, such as letters, diaries, or autobiograpies
• results of experiments and/or statistical data, including surveys
• audio and video recordings
• interviews, conversations, or speeches
• direct Internet communications such as email, blog posts, listserv comments, and newsgroup

Secondary Sources are:

• written or recorded materials that describe, discuss, interpret, comment upon, analyze, and/or evaluate primary sources.
• commentaries, histories, biographies
• review articles in academic journals
• books or articles written to analyze how a historical era, person, or event is relevant to our world now

Primary sources present facts and data, while secondary sources ask questions and find answers concerning what those facts and data might mean.

• Was the author/creator directly involved in the event the document talks about?  If yes, it's a primary source.  If no, it's a secondary source.
• Was the document written during or shortly after the time the event happened?  If yes, it's a primary source.  If no, it's a secondary source.
• Does the document focus on presenting facts, data, and results without interpretation?  If yes, it's a primary source.  If facts, data, and results are presented along with analysis, review, interpretation, or evaluation, it's likely a secondary source.