The principal markets that exist for industrial infrared systems are considered. There is a discussion on the relevance of detector figures of merit and specifications. The particular needs of each part of the industrial market - consisting of thermal imaging, pyrometry, intruder alarms, flame and fire detectors, and process composition analysers - are summarised. Individual detectors are then considered, but this is restricted to types of known industrial application, and the limitations and advantages of each one listed. There is a brief discussion of amplifying and cooling requirements.