Oral history is the collection and study of historical information from people, families, important events, or everyday life using audiotapes, videotapes, or transcriptions of planned interviews. These interviews are conducted with people who participated in or observed past events and whose memories and perceptions of these are to be preserved as an aural record for future generations. Oral history strives to obtain information from different perspectives and most of these cannot be found in written sources. Oral history also refers to information gathered in this manner and to a written work (published or unpublished) based on such data, often preserved in archives and large libraries. Knowledge presented by oral history is unique in that it shares the tacit perspective, thoughts, opinions and understanding of the interviewee in its primary form.

The term is sometimes used in a more general sense to refer to the study of information about past events that witnesses told anybody else, but professional historians usually consider this to be the study of oral tradition or traditional oral history due to the source receiving the information aurally.

It is believed that the term oral history originates with Joe Gould, a homeless man living in New York City who solicited donations by claiming that he was working on a massive manuscript called "An Oral History of Our Time", which he said consisted of thousands of recorded conversations on various topics. Although he was known to have a history of mental illness and violence, Gould was beloved by some writers in Greenwich Village, including Ezra Pound and E. E. Cummings. His writing, supposedly excerpts from this "Oral History", was published in elite literary magazines, and he was eventually profiled in The New Yorker.

One of the earliest academic oral history projects was Columbia University's Oral History Research Office, which was established in 1948 by Professor Allan Nevins. It consists of almost 8,000 taped memoirs and nearly 1,000,000 pages of transcript; it is the oldest and still largest organized oral history programs in the world.

Oral history has become an international movement in historical research. This is partly attributed to the development of information technology, which allowed a method rooted in orality to contribute to research, particularly the use of personal testimonies made in a wide variety of public settings. For instance, oral historians have discovered the endless possibilities of posting data and information on the Internet, making them readily available to scholars, teachers, and ordinary people. This reinforced the viability of oral history since the new modes of transmission allowed history to get off archival shelves and reach the larger community.

Oral historians in different countries have approached the collection, analysis, and dissemination of oral history in different modes. There are many ways of creating and studying oral histories even within individual national contexts.

According to the Columbia Encyclopedia:, the accessibility of tape recorders in the 1960s and 1970s led to oral documentation of the era's movements and protests. Following this, oral history has increasingly become a respected record type. Some oral historians now also account for the subjective memories of interviewees due to the research of Italian historian Alessandro Portelli and his associates.

Oral histories are also used in many communities to document the experiences of survivors of tragedies. Following the Holocaust, there has emerged a rich tradition of oral history, particularly of Jewish survivors. The United States Holocaust Memorial Museum has an extensive archive of over 70,000 oral history interviews. There are also several organizations dedicated specifically to collecting and preserving oral histories of survivors. Oral history as a discipline has fairly low barriers to entry, so it is an act in which laypeople can readily participate. In his book Doing Oral History, Donald Ritchie wrote that "oral history has room for both the academic and the layperson. With reasonable training... anyone can conduct a useable oral history." This is especially meaningful in cases like the Holocaust, where survivors may be less comfortable telling their story to a journalist than they would be to a historian or family member.