The autobiography, perhaps most importantly, allows the writer to tell his own story in his own words. Autobiographies also have the distinct advantage over books written by someone else in that they can contain the writer's inner thoughts and key events that no one else witnessed besides the author.
Most writers choose to write their autobiography late in life, after accumulating a significant number of important or interesting experiences. Occasionally, younger writers will also write an autobiography after a particularly memorable period in life, such as an addiction and recovery cycle or after traveling abroad.
Some of the most successful autobiographies have come from public figures. Many presidents have written autobiographies--Ulysses S. Grant, Theodore Roosevelt and Barack Obama, for example. Hollywood celebrities such as Johnny Cash, Gloria Vanderbilt and Mick Foley have also penned popular books.
While the term "autobiography" refers to a book written by the author about herself, this is not always strictly the case. Some autobiographies are written with the help of professional writers who may or may not be credited.
While having the writer as the primary source of the material is often an advantage, it should be noted that the author may embellish his life story, or even fabricate entire portions of it. Whenever possible, corroboration of especially important or outlandish claims is encouraged.