About 200 years ago in 1815 Sir James Hall made his famous analogue experiments, which showed probably for the first time that natural folds in ductile rock are the result of a horizontal compression. If such rocks are extended, then the rock layers can thin only locally, which is a process termed necking, and the resulting structure is often termed pinch-and-swell. We review here theoretical and experimental results on folding and necking on all geological scales.