  We review the recent developments in electronic Raman scattering measurements
of charge nematic fluctuations in iron-based superconductors. A simple
theoretical framework of a $d$-wave Pomeranchuk transition is proposed in order
to capture the salient features of the spectra. We discuss the available Raman
data in the normal state of 122 iron-based systems, particularly Co doped
BaFe$_2$As$_2$, and we show that the low energy quasi-elastic peak, the
extracted nematic susceptibility and the scattering rates are consistent with
an electronic driven structural phase transition. In the superconducting state
with a full gap the quasi-elastic peak transforms into a finite frequency
nematic resonance, evidences for which are particularly strong in the electron
doped systems. A crucial feature of the analysis is the fact that the
electronic Raman signal is unaffected by the acoustic phonons. This makes Raman
spectroscopy a unique probe of electronic nematicity.
