ESDU 02006 is one of a series on temperature measurement. Its purpose is to review the general techniques available for measuring temperature and to consider specific instruments for particular applications. Twenty-seven temperature measurement systems are covered and measurement criteria appropriate to each device are described or stated. These criteria include calibration@ temperature range@ response characteristics@ transient capability@ sensitivity@ uncertainty@ thermal disturbance and measurement repeatability. Commercial availability and relative costs of devices are also stated. Based on the relative merits of different techniques@ guidance for the selection of an appropriate temperature measurement technique is provided. This information is intended for an initial system selection; more detailed information on design and installation of the chosen system will be found in the specific guides@ ESDU 06018 on thermocouples and ESDU 06019 on resistance thermometry.