  Faraday tomography, the study of the distribution of extended polarized
emission by strength of Faraday rotation, is a powerful tool for studying
magnetic fields in the interstellar medium of our Galaxy and nearby galaxies.
The strong frequency dependence of Faraday rotation results in very different
observational strengths and limitations for different frequency regimes. I
discuss the role these effects take in Faraday tomography below 1 GHz,
emphasizing the 100-200 MHz band observed by the Low Frequency Array and the
Murchison Widefield Array. With that theoretical context, I review recent
Faraday tomography results in this frequency regime, and discuss expectations
for future observations.
