This thesis is centered on the angular power spectrum of galaxy number counts. It studies various aspects of this useful quantity and its ability to tell us about the Universe. These include an examination of the accuracy of its approximation in the flat-sky regime, an analysis of the reapportioning of power to its low multipoles as a result of narrow redshift window functions, and an investigation of a new observable based on fluctuations in redshift instead of density, and its effectiveness in constraining cosmological parameters.