When John Grierson first coined the word in 1926, he described documentary as the 'Creative treatment of actuality.'
In film, a 'documentary' or 'doc' refers to a piece which strives to record or represent an event, a life story or a social issue. This can be done using actual footage or as a reconstruction. Often they are made around a fact or statement however, they are also often found to be based on a question or hypothesis, and, in accordance with this, they often use a lot of facts, statistics and other data which could be gathered from primary or secondary sources.
A common convention of film documentaries is to use, either full or sections from, video or audio interviews which are a great primary source of data that can prove to be very helpful in obtaining firsthand information which is high in validity. Of course, due to these interviews often being unstructured, or at the very least unscripted, they don't tend to be the most reliable or reproducible sources of information. Which is why official facts and statistics are so often used in addition to these.
However, one of the good things about this convention is the fact that it helps in achieving the aim of a documentary which is to inform an audience to the point that they are able to form their own opinion on the person, event or issue. Sometimes the writer or director will have particular opinion that they want their audience to form in which case they will bias the representation within the documentary to fit this purpose. However, as we know due to the several different audience reception theories including negotiated and oppositional, the way the audience receives the piece still may not always be as desired.
Another common convention of documentaries, in terms of the narrative, is the use of narration. Common forms of this include voice over or an on camera host which help to put across the events or opinions shown within the documentary, to the audience. This therefore, is one of the many ways in which they are different to dramas. This is why, unti much more recently, say the last 20 years or so, documentaries and dramas attracted very different audiences. As well as, of course, each different type and genre of documentary attracting it's own individual, 'niche' audience due to it's subject matter.
However, for mainstream audiences documentaries weren't very popular and therefore often missing out on the market for young people due to their non fiction narrative style and the lack of common drama conventions such as action explosives, special effects and fantasy or animated characters. Moreover, this meant that those who weren't educated or well informed film lovers who were able to appreciate all types of good cinema, a stigma formed around documentaries, about them being 'boring' and 'uncreative' or not being fun, interesting or beautiful to watch.
However, in recent years they've become much more popular not just critical, but also commercial success. They continue to enter the mainstream market, and our increasingly becoming just as popular as dramas for not only film lovers, experts or critiques like they were previously, but also your average mainstream media consumer. The market for documentaries at the moment is really booming both in terms of films but also TV series on popular mainstream channels as well as worldwide film/TV show streaming sites such as Netflix. Some recent examples include the series 'Making A Murderer' (2015) as well as films such as Bowling For Columbine (2002), Super Size Me (2004), The Act of Killing (2012), Blackfish (2013) and Amy (2015).
