Pride and prejudice takes places during a time called the Regency Period which originally began in 1811. During this time and into the early nineteenth century, inheriting land and ownership was very important in England society.
The upper class, was born into their wealth and usually came with a lot of nobility. They inherited money, all the land and other possessions that went with it. People in this higher class system only associated themselves with people of equal or higher rank. An example of this would be the way Mr. Darcy carries himself as, he does not reach out to people of the lower class like Mr. Bennet,or Mr. collins. That was typically behavior during this time period which could also be seen in Miss Bingley letter to Jane. Some of your higher class people consisted of lords, and officers of state.
The middle class, a class of merchants and businessmen who made their money in trade. Before the Industrial Revolution was introduced they had very little political power but grew largely, due to there size and increase in money. Examples of middle class people would be your teachers,shopkeepers,lawyers and artists.
The working class are your peasants who had come to the city to work. They barley made any money if ever, inherited any money. They had little wealth and no political power.