The three sources most used are books, periodicals, and websites. Most information will probably be secondary information instead of primary information. This page attempts to clarify the difference between primary and secondary information.
A simple explanation of primary information is that it is original
information. For example, a scientist's findings based on
experimentation is considered primary. An interview that you conducted
and documented is also primary. Secondary information usually explains
or analyzes primary information.
This short YouTube video created by UCSD Social Sciences and Humanities Library uses a historic event to illustrate the difference between Primary Sources and Secondary Sources. Click the title to start the video.(UCSD) Used with permission from UC-San Diego Library.