Classical political economy including Marx designed the labour theory of value. A macro theory of wages based on the cost of labour borne by capitalists became the wage fund theory grounded on the supply side. Wages were seen as a distribution issue between labour and capital. Jevons (The Theory of Political Economy, Oxford University Press, 1871) shifted towards the demand side linking wages as income to labour productivity within a micro theory of individual choice. The full neoclassical theory of wages (Hicks 1932) includes labour market equilibrium between supply and demand, with flexible wages adjusting the level of employment. Keynesian theory shifts back to macroeconomics, emphasising the level of employment as an adjustment on the market for goods and services rather than on the labour market. Human capital theory (Mincer, Journal of Political Economy, 66(4), 281–302, 1958), a major development in microeconomic wage theory, focused again on labour supply. In the 1970s and 1980s, New Keynesian theory introduced wages as a microfoundation for macroeconomics on the supply side, addressing turnover and shirking, and comprising the insider-outsider theory on the demand side. Labour market segmentation theory emerged in the early 1970s with the invention of the “informal sector” in Africa. Coupled with dual labour market theory (Lewis, The Manchester School of Economic and Social Studies, 22, 139–191, 1954), it opposed neoclassical theory, contending that wages do not reach equilibrium in the informal segment, which prevails in Africa and proves involuntary rather than voluntary. Feminist economists introduced gender issues from the demand side challenging the neoclassical approach to gender discrimination from the supply side. The book addresses several stylised facts highlighting various aforementioned theories.