Primary Sources are immediate, first-hand accounts of a topic, from people who had a direct connection with it. Primary sources can include:
Texts of laws and other original documents.
Newspaper reports, by reporters who witnessed an event or who quote people who did.
Speeches, diaries, letters and interviews - what the people involved said or wrote.
Datasets, survey data, such as census or economic statistics.
Photographs, video, or audio that capture an event.
Secondary Sources are one step removed from primary sources, though they often quote or otherwise use primary sources. They can cover the same topic, but add a layer of interpretation and analysis. Secondary sources can include:
Most books about a topic.
Analysis or interpretation of data.
Scholarly or other articles about a topic, especially by people not directly involved.
Documentaries (though they often include photos or video portions that can be considered primary sources).