Primary sources can be many things. What they all have in common is that they are original material based on first-hand experience or observation. Examples of primary sources include, but are not limited to:
Secondary sources, by contrast, are typically based on primary sources and/or other secondary sources. Most non-fiction books and other kinds of literature would fall into this category. While neither type of source is inherently "better" than the other, primary sources have the advantage of being closer to actual events, and for this reason they are relied on more heavily at advanced levels of research. Depending on your field of study, you will likely be required to use primary sources at some point.
The box below lists library databases composed partly or solely of primary source material.
Although there isn't an option in OneSearch for filtering search results by whether they are primary or secondary sources, one can use the Resource Type filter group to select only types that would qualify as primary.