Etymology of the word "biography" is emanate from Greece : bios - meaning "life" and graphein - meaning "write". Therefore biography meaning to write about somebody's life.
A biography analyzes individual personality and more personal facts like : birth, place of birth, childhood, teenage, education, occupation, career, culture, work, hobby, relationships, friends, emotions, experiences...and death.
A biography explains a person's character and life ; in general of important people, not ordinary people.

One of the first known biography is The Jewish holy scripture.This refers at the lives of chiefs, kings, tribes, patriarchs and prophets.

First biographies appeared from antiquity : ancient Assyria, ancient Babylonia, ancient Egypt, ancient Mesopotamia, among others.
Ancient Greeks have written "Damascius' Life of Isodorus" , "Herodotus' Histories" and have followed a great tradition of biographies.
The biographical tradition does draw on these types, but it also gives explicit recognition to the importance of individual idiosyncrasies in defining a man, and places the emphasis firmly on a man's personality rather than merely listing his accomplishments. As Plutarch says in the introduction to his Life of Alexander the Great, 'in the most illustrious deeds there is not always a manifestation of virtue and vice, but a slight thing like a phrase or a jest often makes a greater revelation than battles where thousands fall, or the greatest armaments, or sieges of cities'. Thus the individual is recognized as having some value and interest irrespective of the impact of his actions on the broader sweep of history.

Biography is a genre of literature and it can refer to events, sports, etc ; for example : Auto racing biography • Basketball biography • English football biography • Ice hockey biography • Track and field athletics

With the technological advancements created in the late 20th and early 21st centuries, multi-media forms of biography became much more popular than literary forms.Visual and film images were able to elaborate new dimensions of personality that written forms could not.The popularity of these forms of biography culminated in the creation of such cable and satellite television networks as A&E, The Biography Channel, The History Channel and History International. Along with documentary film biographies, Hollywood produced numerous commercial films based on the lives of famous people.

An autobiography is a biography written by the subject or composed conjointly with a collaborative writer (styled "as told to" or "with").
Biographers generally rely on a wide variety of documents and viewpoints; an autobiography may be based entirely on the writer's memory. A name for such a work in Antiquity was an apologia, essentially more self-justification than introspection.

A memoir is slightly different from an autobiography. Traditionally, an autobiography focuses on the "life and times" of the character, while a memoir has a narrower, more intimate focus on his or her own memories, feelings and emotions.

Modern memoirs are often based on old diaries, letters, and photographs. Although the term "memoir" may have begun to replace "autobiography" in its popular usage, the former term applies to a work more restrictive in scope.

Source : www.wikipedia.org