What is the importance of social class in Pride and Prejudice? Are there types of social class?

Social class is highly important in Pride and Prejudice, as it was in the society Austen was depicting. English society in the early 19th century was hierarchical, rather than equalitarian, meaning people's place in society was determined by who their parents were. Strict rules of etiquette governed interactions between individuals of different social classes. For example, nobody of a lower social class was supposed to introduce themselves to someone of a higher class unless spoken to first, which is why it is embarrassing when Mr. Collins introduces himself to Mr. Darcy.

At the top of the hierarchy were royalty and below them the landed aristocrats. Mr. Darcy was a landed aristocrat: he had inherited a vast estate from his father and rented out most of the land, then lived on the rents. The chief mark of a gentleman was not having to work for a living. Mr. Darcy was at the top of the social hierarchy in Pride and Prejudice. Lady Catherine, Mr. Collins's patroness, was also a landed aristocrat.

The Bingleys represented a new kind of wealth rising in England. We are told Mr. Bingley's father was a tradesman who made a fortune in the north. Most likely, he owned a cotton mill and was part of the industrial revolution that was rapidly raising England to the premier world power. But because he worked for a living, no matter how wealthy he was, he ranked below a leisured gentleman like Darcy. However, he had the money to set up his son, Mr. Bingley, as a gentleman of leisure with a large allowance, and his daughters as ladies. We can understand some of Miss Bingley's urgent desire to marry Mr. Darcy if we see it as a way of helping her family climb into the aristocracy: no matter how wealthy they were, they were stained by coming from trade. 

The Bennets were landed gentry: they had an estate big enough to take guests hunting, and they derived a comfortable living from the rents on the estate, but they were not wealthy aristocrats with titles: they were not lords and ladies. Therefore, they ranked below people like Darcy and Lady Catherine on the social scale.

Clergymen like Mr. Collins were considered gentlemen and included in the upper classes: as we see, Mr. Collins spends much time visiting Lady Catherine. But because they did not have landed wealth, they were lower on the social scale than a lord or lady.

We see much jockeying for social position in Pride and Prejudice. Lady Catherine, for example, is furious at the idea that Elizabeth would dare to think she could marry Mr. Darcy.