An historian is an individual who studies and writes about history, and is regarded as an authority on it.  Historians are concerned with the continuous, methodical narrative and research of past events as relating to the human race; as well as the study of all events in time. If the individual is concerned with events preceding written history, the individual is a historian of prehistory. Although "historian" can be used to describe amateur and professional historians alike, it is reserved more recently for those who have acquired graduate degrees in the discipline. Some historians, though, are recognized by equivalent training and experience in the field. "Historian" became a professional occupation in the late nineteenth century at roughly the same time that physicians also set standards for who could enter the field.
The process of historical analysis involves investigation and analysis of competing ideas, facts and purported facts to create coherent narratives that explain "what happened" and "why or how it happened". Modern historical analysis usually draws upon other social sciences, including economics, sociology, politics, psychology, anthropology, philosophy and linguistics. While ancient writers do not normally share modern historical practices, their work remains valuable for its insights within the cultural context of the times. An important part of the contribution of many modern historians is the verification or dismissal of earlier historical accounts through reviewing newly discovered sources and recent scholarship or through parallel disciplines like archaeology.
Concerning Herodotus (5th century BC), one of the earliest nameable historians whose work survives, his recount of strange and unusual tales are gripping but not necessarily representative of the historical record. Despite this, The Histories of Herodotus displays some of the techniques of more modern historians. He interviewed witnesses, evaluated oral histories, studied multiple sources and then pronounced his particular version. Herodotus's works covered what was then the entire known world of the Greeks, or at least the part regarded as worthy of study, i.e., the peoples surrounding the Mediterranean. Herodotus was also known for visiting the various battle sites he wrote about, including the battle of Thermopylae. About 25 years after Herodotus, Thucydides pioneered a different form of history, one much closer to reportage. In his work, History of the Peloponnesian War, Thucydides wrote about a single long conflict that lasted 27 years between Athens and Sparta with its origins and results. But, as it was mainly within living memory and Thucydides himself was alive throughout the conflict and a participant in many of the events, there was less room for myths and tall tales. Moreover, he had the custom of including transcriptions of speeches that were supposedly delivered by historic figures, although, more commonly, they were made up by Thucydides himself according to what he felt those people should have said at the moment they delivered them..
Other noteworthy and famous Greek historians include Plutarch (2nd century AD), who wrote several biographies, the Parallel Lives, in which he wanted assess the morality of its characters by comparing them in pairs, and Polybius (3nd century BC), who developed Thucydides's method further, becoming one of the most objective historians of classical antiquity. Polybius is also credited for being the first historian to write a History of the World, and to offer argued explanations and interpretations of history facts, and not only a record of them. However, the most important historian of the classical world was Tacitus (late 1st and early 2nd century AD). The foremost roman historian, he wrote an extremely influential account on the first century roman history, the Annals; because of his literary style –sober, elegant, and somewhat obscure–, the thoroughness of his research –which seemingly included studying roman imperial archives, and which was heavily influenced by Thucydides–, and his apparent rigor –for he tended not to support any character or subject, taking an impartial point of view–, he was by far the most read and admired historian during the Middle Ages, the Renaissance and the early Modern Era; thus, his historian style has been imitated all through the ages, and had a severe impact in Edward Gibbon and Montesquieu, usually considered as the first modern historians.
Sima Qian was a Prefect of the Grand Scribes (太史令) of the Han Dynasty and is regarded as the father of Chinese historiography because of his highly praised work, Records of the Grand Historian (史記), an overview of the history of China covering more than two thousand years from the Yellow Emperor to Emperor Han Wudi (漢武帝). His work laid the foundation for later Chinese historiography. Li Chunfeng was a Chinese historian who wrote the history of the Jin dynasty. (漢武帝).
Ibn Abd-el-Hakem was an Egyptian who wrote the History of the Conquest of Egypt and North Africa and Spain, which was the earliest Arab account of the Islamic conquests of those countries. Much like Herodotus' works, it mixes facts with legends, and was often quoted by later Islamic historians. Al-Jahiz was a famous Arab scholar and historian. Hamdani, an Arab historian,was the best representatives of Islamic culture during the last effective years of the Abbasid caliphate. Ali al-Masudi was an Arab historian, known as the “Herodotus of the Arabs.” Ibn Khaldun was a famous Arab Muslim historian and was the forefather of historiography and the philosophy of history. He is best known for his Muqaddimah "Prolegomenon".
Much of the groundwork in creating the modern figure of the historian was done by Charles de Secondat, baron de Montesquieu (1689–1755). His wide-ranging Spirit of the Laws (1748) spanned legal, geographical, cultural, economic, political and philosophical studies and was greatly influential in forging the fundamentally interdisciplinary historian. Referred to as "the first modern historian", Edward Gibbon wrote his magnum opus, The History of the Decline and Fall of the Roman Empire (three vols., 1776–1788). However, some authors such as Christiansen regard ancient Greek author Polybius as the first historian of a modern kind, criticising sources and making unbiased judgements based on presumed neutral analysis; indeed, Livy used him as a source. Polybius, one of the first historians to attempt to present history as a sequence of causes and effects, carefully conducted his research—partly based on what he saw and partly on the communications of eye-witnesses and the participants in the events.
At the dawn of the twentieth century, Western history remained oriented toward the "great man theory" of history concerning war, diplomacy, science and high politics. This point of view was predisposed toward the study of a small number of powerful men within a given socio-economic elite. More often than not, this has been furthered by the traditional whig school of thought, which holds that history is "protestant, progressive... [and] studies the past with reference to the present." This has been gradually been replaced with a more critical perspective. For example, it is a common misconception that Thomas Edison alone invented the incandescent light bulb; a traditional history might highlight Edison's invention at the expense of all others. In contrast, a modern history of Edison or the lightbulb mentions Joseph Wilson Swan, Heinrich Göbel, A.N. Lodygin, and Warren De la Rue in order to show that Edison's activities were one part of a group of inventors and rivals in the commercial deployment of the technology.
Since the 1960s, history as an academic discipline has undergone several evolutions. These changes fostered advances in a number of areas previously disregarded in historiography. Formerly neglected topics have become the subject of academic study, such as the history of popular and mass culture, sexuality, cultural geography, and the lives of ordinary people. Starting in the 1960s--and some would say earlier--revisionist historians have attempted to "set the record straight" by redefining the impression society holds of the past. For instance, in his ground-breaking Roll, Jordan, Roll, historian Eugene D. Genovese focused not on white Southern slaveholders--as more traditional historians have done--but on the experiences of African Americans under slavery--hence the subtitle, "The World the Slaves Made". Edward Said's Orientalism is another revisionist classic, in which Said examines how and why Western societies so quickly came to consider non-Western ones as inherently inferior. One of the most popular revisionist works is Howard Zinn's 1980 book, A People's History of the United States, where Zinn attempts to discuss all those left out of "great man history": workers, slaves, women, blacks, Hispanics, Asians, and leftist political radicals and activists.
While revisionist history has resulted in the flowering of new historical approaches and subjects, some historians are divided on just how positive this change is. Most historians are pleased with this proliferation of historical subjects and actors, such as the growth of the history of sexuality and gender analysis--which includes both women's history and the study of masculinity. Scholarship on various ethnic or racial groups has grown, especially in American history: historians now focus on the experience of blacks, Asians, and Hispanics in America, as well as the lives of Irish, Italians, and other Southern or Eastern European immigrants groups. That said, some historians have complained of the fracturing and atomization of the historical field. As historians examine increasingly smaller subjects, few historians are willing (or able) to tackle all of the various historiographies relevant to a broader interpretive or analytic synthesis. Indeed, scholars have been calling for a "new synthesis" in American history for a good decade now.
Many historians are employed at universities and other facilities for post-secondary education. In addition, it is common, although not required, for many historians to have a Doctor of Philosophy (PhD) degree in their chosen areas of study. During the preparation of their thesis for this degree, many develop into their first book, since regular publishing activities are essential for advancement in academia. There is currently a great deal of controversy among academic historians regarding the possibility and desirability of the neutrality in historical scholarship. The job market for graduate historians is relatively limited. Historians typically work in libraries, universities, archival centers, government agencies (particularly heritage) and as freelance consultants. Many with an undergraduate history degree also may become involved with administrative or clerical professions and an undergraduate history degree is often used as a "stepping stone" to further studies such as a law degree.
History is the study of human behavior through time. When used as the name of a field of study, history refers to the study and interpretation of past humans, families and societies as preserved primarily through written sources.