Primary sources are first-hand accounts or objects from the past, while secondary sources are later accounts of past events. When analyzing primary sources, historians consider factors like the creator's perspective and potential biases. Most evidence has some bias, so historians critically examine sources and compare them to get a full picture of events from the past. Different types of sources like documents, photographs, maps, artifacts, and political cartoons require considering specifics about their context, purpose, symbols, and what details are included or excluded.