Nitrogen oxide formation is one source of pollution emission in fossil fuel combustion. Numerous technologies, such as flameless combustion, have been introduced to prevent such formation. This paper presents a panorama of flameless combustion and its principles. The influence of this technology on air preheats and gas diluents is discussed, as well as the effect of the firing mode on thermal NOX. The benefits of flameless combustion, including its energy conservation capability and capability to reduce pollutant emissions such as NOX emission to overcome environmental dilemmas in combustion, are discussed in this paper. Copyright (c) 2014 John Wiley & Sons, Ltd.