Pyrometers and thermography cameras used to be characterized by different specifications and technical definitions. After an analysis of the market situation and the physical basics, the following article describes common methods to determine optical and thermal key parameters. Based on this, aspects of future sensor developments and certain applications of infrared (IR) cameras are discussed. <br><br> (This article was first published in the journal <i>tm – Technisches Messen, Vol. 81, No. 3, 2014</i>, a volume which is dedicated to the memory of Prof. Dr.-Ing. habil. Ludwig Walther.)