A primary source is original, firsthand information. It hasn't been interpreted, analyzed, condensed, or changed.

It can be in the form of a creative work, diary, speech, letter, interview, news film footage, autobiography, photograph, official record, historical document.

It can be an email written by a researcher to a colleague which includes data from an experiment. It can be a professor's lecture.

It can be a newspaper article written at the time of an event or the transcript of a television report of an event.

It could even be a tweet or other dispatch via a social media outlet like facebook, as in the case of the events surrounding the "Arab Spring" or, more locally, in the case of the military jet crash in April 2012 in Virginia Beach, or the August 2011 earthquake in Virginia.

Examples:

A photograph taken in 1992 during the Los Angeles riots.	The Diary of Anne Frank	A Letter from former Virginia Governor Almond
	(an autobiography)

Information may need to be constructed with raw data from primary sources.

In the humanities, primary sources may be books or historical documents or artworks.

In the social sciences, a primary source may be transcripts of interviews with people, or data collected from surveys.

In the sciences, primary sources may be data collected from experiments.