Primary sources are generally materials created at the time of an event and reflect the individual viewpoint of the participant or observer. For the study of government and politics these include speeches, letters, diaries, autobiographies, interviews, official government records such as the Debates, Acts, treaties, regulations and reports, documentary photographs, video or film recordings of an event, public opinion polls, press releases, the records of political organizations, the results of original research, etc.
Distinguish these from secondary sources which are works about primary materials and the people who produced them. Secondary sources are at least one step removed from the actual event, person, or primary source, providing a second-hand view, such as an interpretation, review, analysis, or report about an event after the fact. (Note that a journal article can be a primary or secondary source depending on how and when it was written.)
For almost all researchers, the secondary sources will be consulted first, and will provide the background knowledge and general understanding of the issue or topic to be studied. It makes sense to consult the work of experts on the topic, those who have examined and analyzed the issues already. However, a good, in-depth research project will also include primary sources that document the issues described and may even provide a better understanding or support a different interpretation than the ones made by previous researchers.
Using primary materials well requires a good understanding of the topic and its context in time and place. Since it is the "raw" material, provided without interpretation, or analysis, the researcher has to be aware of local or historical circumstances that might influence how the material is to be interpreted.
A good knowledge of the subject is required just to locate primary materials. More so than for other kinds of materials, primary sources can be difficult to research without knowledge of the terminology used at the time of the event, the names, dates, places, and other key facts involved with the event, and the broader context of the topic. For example, it is very little use searching the House of Commons Debates for a speech by the Prime Minister at the time of the outbreak of World War II, if you do not know the time period this occurred, or the name of the Prime Minister.
Primary source material can be difficult or time-consuming to obtain. Fortunately, not all historical primary sources need to be consulted in their original, often fragile form. Many significant primary texts are being reprinted or digitized to make them more accessible to researchers everywhere.
Using primary sources can be the most rewarding part of a research project. These materials, which represent the subject itself, bring the subject to life and create a direct link between the subject and the researcher.