Historians use two different types of sources: primary and secondary.

Primary sources are original documents from the past. These include tax and census records, letters and diaries, archaeological artefacts, etc. Most of these are held in state and private archives, museums, etc, and studying them typically requires years of hard labor. A PhD in history trains you to read, analyze, and use these kinds of documents to write secondary sources--books about the past. My own research involves studying burial records from 850 graves, thousands of archaeological artefacts, and 300-odd cemeteries from the middle ages. This will in a few years be boiled down into a 200 page book, and that book will be the 'history' that a person can actually read to figure out what happened in the past.

Secondary sources are books and articles written by modern historians. These are the best way to get an overview of a topic, and to engage with the ideas and debates that historians who specialize on these topics are having with each other.

Some secondary sources are more approachable than others. Much of what historians write is written for other historians. This is because a large part of what historians do is compare findings with our peers, and see how these findings help to support, clarify, or challenge the work that others are doing. Like the sciences, where researchers conduct experiments to test, confirm, reject, or improve other researchers' theories, historical research involves a lot of work talking about how new analyses add to or challenge older scholarship.

These kinds of books and articles (which are usually published by university presses and scholarly journals) can often be challenging reads if you're not a specialist. It sometimes feels like you're at a party where everyone else knows, and wants to talk to, each other instead of talking to you.

In most sub-fields of history, however, there are books written deliberately to share historians' conclusions with a wider readership of non-specialists. Those are the books you want to read if you're curious about the latest views on what happened. They're written by real scholars who know what they're talking about, they're generally priced lower than the specialist books, and they're written to make sense to someone who doesn't have an MA on the topic already.

How do you know if a history book you find on the shelf is written for specialists or curious non-specialists? How do you know if it's written by a real historian, or an enthusiastic amateur? There are a few good clues. First, does the author have a PhD? Does she work at a university? If the answer to those questions is yes, you've probably got a work of good history in your hands. To tell if it was written for a specialist or not, flip through the introduction and see what kinds of questions the book is addressing. If it uses a lot of jargon, talks a lot about other historians that you've never heard of before, or dives deep in theory, odds are it's written for a professional audience instead of curious laypersons. If it's priced at $60+, it's also probably written for specialists.

What about popular articles, podcasts, etc? These can be great. They can also be full of misinformation. Much depends on who is writing the content (are they historians? interested amateurs? journalists? conspiracy theory nuts?), and who publishes it. People here may be able to make some recommendations of particularly good podcasts, etc, if that's what you're looking for. Ultimately, books written by trained historians are going to be more reliable than online content. Take advantage of your local library; if they don't have a big history section, they can probably interlibrary loan you good books, and they may have access to non-fiction ebooks as well.

Do check out our booklist! It has a lot of great reading recommendations on a variety of topics, and we've tried to recommend titles written for educated laypersons like yourself rather than historical specialists.

It completely depends on what you're writing about. Generally, the bread and butter for historians is written records these tend to be the most accessible sources that you can have. Court records tell you about a culture's legal system, advice manuals tell you about what a culture thought ideals were between men and women, newspaper editorials tell you what people were worrying about at a given moment in time. If you are doing ancient history or a culture which did not leave many written records then you might have to rely to a greater extent on archaeological and art historical evidence. So what do Frankish burial practices tell us about them in the absence of any books by them telling us directly? They are buried with their horses, perhaps indicating that they still had some belief in pagan gods, but also with crosses suggesting that they might be in the process of converting to christianity with some elements of their former faith preserved etc. Recently historians have begun to get very creative with their sources -- particularly when they are trying to reach the mentalities of people who do not leave written records such as peasants. I read a very interesting article a few weeks ago which used four Grimm's fairy stories as evidence for the attitudes of peasant women in Hesse to draft policies around 1760. But this is an acknowledgement that the existing sources that we have, from nobles and other educated types, do not seem to capture the reality of peasant life and therefore we have to look elsewhere.

As to where historians physically get their sources, archives tend to be the best places to look. National archives like the Bibliotheque National and the British Library hold treasure troves of source information which are relatively easy to access. Things like government records, newspapers and so on going quite far back. If you are looking for a specific person then it is relatively likely that their writings have been preserved somewhere. So all the papers surrounding the establishment of the Shrine at Lourdes are there in Lourdes -- any historian wanting to get at the primary documentation would have to go there and copy out the letters or take scans themselves. The same goes for all of Rimsky-Korsakov's correspondence (the Russian composer) is in his archive in Tikhvin or in the bottom of a filing cabinet somewhere in the St Petersburg conservatory. Generally for historians primary research is a matter of having a reasonable idea what you are looking for and then heading off somewhere in the hope that they might have what you need.