In addition to the primary CMB anisotropies from the last scattering surface, in the microwave sky there are also point (or compact) sources. These include galaxy clusters, seen in the microwave through the thermal and kinetic Sunyaev–Zeldovich effects, radio galaxies, and dusty galaxies, also known as the Cosmic Infrared Background (CIB). These sources become more significant at large multipole number, having a white noise angular power spectrum (when correlations or clustering is neglected). The angular power spectrum of these objects is reddened when clustering is taken into account.