A quantum fluid is one in which energy quantization has a marked effect on behaviour. Sometimes the effect can be dramatic, as with superfluid helium and with the electron gas in superconducting metals. In this article a simple criterion for distinguishing quantum fluids is obtained, and this is followed by a brief outline of the properties of perfect quantum gases. These ideas are then used as a unifying framework, within which some properties of real quantum fluids sre described and analysed. The approach to the subject is descriptive and physical, with very little dependence on mathematical argument.