A source text is a text (sometimes oral) from which information or ideas are derived. In translation, a source text is the original text that is to be translated into another language.

In historiography, distinctions are commonly made between three kinds of source texts:

Primary sources are firsthand written evidence of history made at the time of the event by someone who was present. They have been described as those sources closest to the origin of the information or idea under study. These types of sources have been said to provide researchers with "direct, unmediated information about the object of study." Primary sources are sources which, usually, are recorded by someone who participated in, witnessed, or lived through the event. These are also usually authoritative and fundamental documents concerning the subject under consideration. This includes published original accounts, published original works, or published original research. They may contain original research or new information not previously published elsewhere. They have been distinguished from secondary sources, which often cite, comment on, or build upon primary sources. They serve as an original source of information or new ideas about the topic. Primary and secondary, however, are relative terms, and any given source may be classified as primary or secondary, depending on how it is used. Physical objects can be primary sources.