My report is dedicated to the oracles in software testing. When you hear about oracle, you may think about Delphic Oracle or about the old woman from Matrix movie, who baked cookies and predicted the fate. But in software testing this term means the mechanism and principle, that helps us to determine the test result. In my report I'll speak about most popular oracle classifications and how they can be used in the error detecting, test design and writing credible bug reports. Oracles are one of the fundamental software testing terms and knowledge about them will be usefull for any tester. I hope that my report will motivate you for furher oracles learning and using them in the everyday work.