From top to bottom:
1.
Top Out-of-sight. This is a secretive and rare class of rich people who generally avoid the limelight. These would be nobility in other countries. Rockefeller, Mellon, Vanderbilt, etc.
2.
Upper. They live on the proceeds of inherited wealth from before they were born. Members of the Walton family who remember Sam Walton are not yet upper class. Those who never really got to know him are upper class.
3.
Upper middle. This is the class on the make -- they include many of the rich who have made it largely on their own and most people in the highly-regarded professions (law, medicine, architecture). This is as high as anyone can get socially except through marriage.
4.
Middle. Generally a white-collar job with a middle income. Accountants, dentists, research scientists, engineers, traveling salesmen, computer programmers, and teachers are here.
-- THERE IS NO LOWER MIDDLE CLASS --
What used to be considered lower-middle class for having a high-school diploma when such was a real distinction and when clerical work paid better than labor. People can no longer make a living on a job as a retail sales clerk or office clerk. Such jobs are typically interchangeable with labor. They typically have college degrees.
There are three classes of the "working class":
5.
High prole -- skilled laborers, cops, nurses, technicians, fire fighters, prison guards, letter carriers, supervisors of blue-collar workers. These may be paid better than members of the middle class, but their jobs are not interchangeable. Accountants don't become heavy-equipment operators and plumbers do not become traveling salesmen.
6.
Mid-prole: semi-skilled workers -- machine operators and assemblers, truck drivers and cabbies. This is probably the class of the checker-cashiers; they operate cash registers, which takes some modest skill. Their work is usually monotonous... and they typically hate their jobs and show it off the job.
7.
Low-prole: unskilled workers like agricultural laborers and janitors. Even if their jobs are seasonal, they are still working-class.
Below this:
8.
Destitute: People with disreputable earnings -- welfare, aid from relatives, or crime. If crooks they are somehow able to avoid incarceration.
9.
Bottom out-of-sight: Hermits; people institutionalized or incarcerated.
Many people don't fit one of these categories neatly. People who think the class game is a fraud -- often creative people -- might fit a category "X". Creative people are often here.