Primary sources are actual records from the past that provide firsthand accounts, including published documents like books and newspapers as well as unpublished documents like letters and diaries. Visual documents and oral histories are also primary sources. Secondary sources are accounts created after the event by people not directly involved, drawing on primary sources and evidence from the time. When analyzing sources, historians consider how close in time and place the source is to the event, as more direct sources are generally more reliable. All sources have some bias, so multiple sources must be evaluated and compared.