An astonishing variety of systems show properties that fluctuate with approximately $\frac{1}{f}$-shaped spectral densities. In this review we deal with selected topics regarding $\frac{1}{f}$ fluctuations (or noise) in the resistance of simple condensed matter systems, especially metals. We find that considerable experimental and conceptual progress has been made, but specific physical processes mostly remain to be identified.

DOI:https://doi.org/10.1103/RevModPhys.53.497