First, historians think about where, when and why a document was created. They consider whether a source was created close in location and time to an actual historical event.
Historians also think about the purpose of a source.
Some primary sources may be judged more reliable than others, but every source is biased in some way. As a result, historians read sources skeptically and critically. They also cross-check sources against other evidence and sources. Historians follow a few basic rules to help them analyze primary sources. Read these rules below.