The term good Samaritan derives from the biblical passage in Luke 10:30/33 of the New Testament. It is a description of how a man who is attacked by thieves is helped by a Samaritan, who was not even a person of the Jewish faith. Several people ignore the man before the Samaritan helps. This suggests the inclusion of gentiles into Christianity, a religion that will embrace not only the Jews but also all who believe in the one God and who follow the teachings of Jesus Christ.
Since that biblical passage, which is a parable told by Christ according to Luke, a good Samaritan has come to mean any person who helps another without thought for reward. A person performing the Heimlich maneuver, for example, to save someone from choking to death could be described using this term. A person who risks her own life to save someone from a burning house or car is also a good Samaritan.
In most cases, the term does not apply to people paid to perform such acts. For example a doctor performing CPR at a hospital is not a good Samaritan, since he or she is paid to do so. A fireman who rushes into a burning building is heroic, but is also doing his job.
Some people disagree with this distinction, however, particularly in the second example. A fireman is risking his life every time he attempts to save someone under dangerous circumstances. Thus some would consider him or her a good Samaritan even though he or she might be paid for such risk.
For a time, people became somewhat leery of helping others in fear of getting sued by those they attempted to rescue. Especially in the US, for a while, a person who tried to help others was not always protected by the law, and this discouraged people from stepping in to help in a time of need. If a person performed CPR and cracked someone’s rib, for example, he could be sued even if he saved the person’s life. There are now good Samaritan laws in place in most places to protect people from lawsuits when they attempt to save or render help to a person in need.