Primary and Secondary Sources
A primary source is a source of information that comes straight from where it comes from. Things like a survivor from a building fire or the fire fighters that helped out with putting out the fire. These people would be primary sources for an article about the building fire. Another source thats a primary source is a document written by someone involved in the event. Such as a book about a war that someone who was in the war wrote.
A secondary source is a source of information from someone or something that wasn't there or at the event. In other words historians are a good secondary source they are pretty accurate based on what they know. Secondary sources aren't as good as primary sources but they still give good information.