There are two common methods used for rheometric measurements on fluid systems: capillary (or tube) and rotational. In this section, a brief summary is given for each general method along with descriptions of common measurement devices and geometries. Measurement devices can be grouped into one of two general classifications. A viscometer is a device used principally for the measurement of viscosity, while a rheometer is a device used for the measurement of rheological properties over a varied and extended range of conditions. Only brief descriptions of these instruments and devices are provided here. For more detailed descriptions, refer to the primary sources listed in the bibliography.