  Multi-Messenger observations and theory of astrophysical objects is fast
becoming a critical research area in the astrophysics scientific community. In
particular, point-like objects like that of BL Lac, flat spectrum radio quasars
(FSRQ), and blazar candidates of uncertain type (BCU) are of distinct interest
among those who look at the synchrotron, Compton, neutrino, and cosmic ray
emissions sourced from compact objects. Notably, there is also much interest in
the correlation between multi-frequency observations of blazars and neutrino
surveys on source demographics. In this review we look at such multi-frequency
and multi-physics correlations of the radio, X-ray, and $\gamma$-ray fluxes of
different classes of blazars from a collection of survey catalogues. This
multi-physics survey of blazars shows that there are characteristic
cross-correlations in the spectra of blazars when considering their
multi-frequency and multi-messenger emission. Accompanying this will be a
review of cosmic ray and neutrino emissions from blazars and their
characteristics.
