1. A technique for the analysis of a very small amount of material by bombarding it with a narrow beam of electrons and examining the resulting x-ray emission spectrum.
2. An analytical technique used to determine the nature of extremely small samples by forming the x-ray spectrum of the samples through excitation by a finely focused electron beam.
3. Identification and measurement of elements and their location based on the fact that x-rays emitted by an element excited by an electron beam have a wavelength characteristic of that element and an intensity related to its concentration.

It is performed with an electron microscope fitted with an x-ray spectrometer, in a scanning or transmission mode.