Primary sources include written documents, images and artifacts from the period being studied. Primary sources need not be replicas or facsimiles of the original. For example, the text of the Declaration of Independence is still a primary source when written or typed out on a website. Depending on the project, some materials that we would often consider secondary sources can also serve as primary sources. An example: if one is using census data from the 1855 US census as support for an argument on poverty in American literature, then the census is a secondary source; but if one is analyzing the census itself, then the census is a primary source.