Definition
Wage labour is the labour relation in which a worker, having no productive assets of their own, sells their capacity to work — their time and effort — to an employer for a money wage. The employer directs the work, owns the product, and keeps any surplus between the wage paid and the value produced. The wage is the price of labour-power, set by labour markets and bounded by what employers can afford and workers can demand.
What makes wage labour distinctive — and historically unusual — is the double freedom Marx noted: workers are free to choose their employer (unlike slaves or serfs) but are also "free" of any other means of livelihood, so they must work for some employer to survive. This combination did not exist in feudal Europe, peasant economies, or slave societies; it had to be made.
Why it matters
How it works
The wage relation makes labour itself a commodity to be bought and sold on a market. This has two consequences. First, labour markets fluctuate: when there is a glut of workers, wages fall; when there is a shortage, wages rise. Second, employers buy a capacity, not a defined quantity of output — so they have an interest in extracting as much work as possible during the bought time, and workers have an interest in defending the pace and intensity of work. Much of workplace politics — overtime, breaks, supervision, surveillance — is the working out of this asymmetry.