Historical sources are, at their most basic level, something that tells us about history. It may be a document, a picture, a sound recording, a book, a cinema film, a television program or an object. Any sort of artifact from the period in question that conveys information can qualify as a source
There are two main types of historical sources: primary sources and secondary sources.
A primary source is something that originates from the past. It can be a chronicle, a piece of pottery, or even a piece of glacial ice that gives us climate data about the levels of atmospheric carbon one thousand years ago. Historians, to the best of their abilities, work with primary sources to understand the past on its own terms, not through the modern-day lenses. For example, if one were only to study the Crusades through modern-day books they would not be able to understand what would motivate a knight to travel across the world and engage in warfare against Muslims in his own words. It would be too easy to view his motivations with our modern-day disapproval of his actions. But if we look at a primary source we can at least sympathize better with the medieval world that would make the act of Holy War seem reasonable to him, even if we still strongly disagree with the outcome.
