The Turing test was designed to be a way of determining whether or not a computer counts as "intelligent". It was created by computing pioneer and arguably the godfather of AI, Alan Turing, in the 1950s.
The test is simple. On one side of a computer screen sits a human judge, whose job it is to chat to a number of people via the terminal. One of the ‘people’ in the chat sessions will be a computer program (essentially a chatbot) created for the sole purpose of tricking the judge into thinking that it is the real human.
Each of the judges has five minutes to talk to each ‘person’ communicating through a machine (terminal), and the computer program passes if more than 30% of the judges think that it was a human.
In 2014 at a test set up at the University of Reading, a program passed the test for the first time ever.
A Russian-designed program called Eugene had 33% of the judges "he" spoke to convinced of his humanity. Though obviously impressive, this is still a long way off achieving the gold standard of modern Turing tests, using rules laid out in 1990 by the inventor Hugh Loebner which require a much longer test of 25 minutes.