What does the term 'based on a true story' mean?

Answer 1

Based on a true story means some of it is true and some of it is not true.

Many movies are based on a true story. The actions, people and words may or may not be true depending on if sufficiently clear records were kept. The more historically distant the less likely it is to be accurate.

Script writers may insert certain facts to give credibility to the rest, thus fooling the more gullible into believing it is all true.

For instance every movie made about WW II could be said to be 'based on a true story'.

As were countless other movies, it does not mean the events or people in the movie were also real.

Answer 2

It means that someone got the idea making the movie from something that happened in real life. so it means that it is a true story