First of all, a "class" is a group of human beings who share common interests, because they experience common conditions.
The working class (sometimes called "proletariat", a French term) consists of all people who must work (another word for "work" is "labor") for someone else in order to make money with which to survive. This includes factory workers, maintenance people, programmers, cooks, dishwashers, secretaries, firemen, etc.
Regardless of a designation of government employees, temp workers, or contract employees, one is still a member of the working class due to the reliance on physical (or mental) work for a wage or salary which pays for ones living expenses (food, clothing, housing medical care, transportation, entertainment).
It also includes artists and tradesmen, because they work for those whom will buy their goods, or they work for some employer who pays for their efforts.. this includes basket weavers, potters, painters, illustrators, tattoo artists, small-time publishers (who work alone to produce a publication), recyclable bottle-collectors, and prostitutes (sex-workers).
The working class does not include those who live off of the work efforts of those in the above mentioned category: employers and landlords... these individuals make up the category of capitalist class because they live off of the concentration of wealth (also called capital) taken through profits generated by the efforts of the working class.
Individuals who pay rent or the unemployed are by default part of the working class because the individual who pays rent must give some of his/her money (generally earned through work) to someone else in order to continue living there. The unemployed must constantly look for work if they cannot somehow survive some way without it, and are always a "reserve" work-force, generally eager to take a decent job when available.
Some people say the working class does not exist anymore or is insignificant. It is true that the nature of the work-force has changed over the last hundred years, but it's quite obvious that everywhere one looks one sees people working for others. In fact, many monotonous, low paying factory jobs still exist, but such jobs have been exported to other countries in the world (outside of the United States) where paying for human labor is cheap due to weak unions & disrespect for human rights (for example, when Chile nationalized it's copper industry in the early 1970's so that American corporations no longer could extract profits from them, closed copper mines in the United States became operational again for a time.)
The term "middle class" is often used by the mainstream media, erroneously, to refer to most Americans who are in fact working class. The "middle class" actually refers to a section of the population which owns small businesses, as opposed to high-level managers and owners of corporations. "Middle Class" is sometimes known as "petit-bourgeoisie" (a French term)... the "petty capitalist class" or "small capitalist class". Some working class individuals who earn high wages, own credit cards, mortgages or deal in the stock market consider themselves "middle class", but the fact remains that they still must work to pay off bills and continue to survive, unless, of course, they run a business.
Those who run businesses with no employees are simply tradesmen who work for those who will buy their goods (as mentioned above).. tradesmen become members of the petit-bourgeoisie the moment they hire another human being to take their place in maintaining the physical effort necessary to earn money, while the tradesman becomes a manager who's main job is to see that the working individual(s) he or she has hired do not waiver from their tasks. This employer has the choice of continuing to do physical work, or he may hire enough people so that he no longer has to do any physical work at all. The fact that he has the choice to not partake in physical effort to earn money, and the fact that those whom he employs are under the constant threat of losing their jobs and living wages if they do not work is what places the worker and the employer into different social classes: the capitalist's interest are in acquiring wealth and keeping the employees in line. The workers interests are to not get fired, and to earn their wage while preserving comfort and as much personal freedom for themselves.
Capitalists concentrate wealth through the efforts of more and more individuals working for them, and more and more acquisitions of land, machinery, and other companies... eventually owning means of communications & news (TV, phone companies, radio stations, newspapers, computer networks), owning means of food production & distribution (farms, supermarkets), owning land, factories, apartment complexes, etc. Eventually capitalists own everything of importance to human survival and happiness this way, which gives them a considerable amount of power and influence over the lives of the rest of the people on the planet. At this point, capitalists are designated to be members of the ruling class. They "rule" over the land and all other things, because they own and control them.
The working class individual can quickly come to the conclusion that unless they see themselves as somehow becoming a member of the capitalist class, or further, the ruling capitalist class, their interests will be forever different from those of the capitalists.
As the pressure for increased work and less benefits increases on the backs of the working class over time, the individual worker must eventually see her or his common rational self-interest inherent in securing his or her own liberty, freedom and comfort, constrained by a capitalist system, by overthrowing and abolishing the capitalist class, and creating a new society which is not based on capitalist class rule.
10/11/95 (watch this space for updates/alterations)