The collection of persons who have a (skilled or unskilled) occupation. Most (but not all) instances of worker spend a significant part of their waking hours doing activities that are characteristic of their occupations. Typically their actions are performed for pay (but not always: consider a starving artist who is unable to sell any of her works). Note that a worker need not be working over the entire duration of when s/he has an occupation; e.g. college professors on summer break and the temporarily unemployed still have occupations. Most reified specializations of worker classify workers according to their job titles, the kinds of work they perform, or the skills involved; while a few exploit other (usually quite broad) features of their working lives (e.g. self-employed person and office worker). But note that many collections corresponding to what are colloquially considered professions or occupations (e.g. lifeguard, StockBroker, housekeeper, and many others) are _not_ specializations of worker, as those collections include people for whom the work in question is not their occupation.