Another truth universally acknowledged is that this opening line is one of the most famous, and most often parodied, in English literature. See here for an entertaining list of variations, including the opening of Bridget Jones's Diary by Helen Fielding, which also borrows the plot of Pride and Prejudice.
Netherfield is a fictional estate located in Hertfordshire.
In his essay 'The Probable Location of "Longbourn" in Jane Austen's Pride and Prejudice', Kenneth Smith suggests that the real inspiration for Netherfield is Kimpton Hall, a long-since vanished estate in the village of Kimpton in Hertfordshire.
A chaise, from the French for chair, is a small light carriage. Some have two wheels, pulled by one or two horses; others have four wheels with as many horses.
This particular quote implies a chaise and four horses. It is mentioned by Mrs Bennet as it shows how wealthy Mr Bingley is.
A Christian feast on 29 September, especially celebrated in the United Kingdom and Ireland, in honour of the archangel Michael.
It celebrates Michael's defeat of Lucifer and Lucifer's banishment from Heaven.
Some sources suggest Michaelmas used to fall on 10 or 11 October.
With a very little literary detective work it is possible to find out how much this means in modern money. The events in Pride and Prejudice are widely considered to begin in September 1811 (see here for more on the book's chronology).
Using the brilliant and rather addictive historical price converter found here (on the right hand side of the page, scroll down towards the bottom) this income equates to an annual income of £260,000- £320,000 ($407,706- $501,792 approx.). Not bad indeed.
In Austen's time, introductions were burdened with rules. A man could not introduce himself to someone of higher standing than himself, nor could he introduce a friend to his acquaintances without their consent. Women always had to wait for men to initiate the introduction, and they could not be introduced to a stranger without an acquaintance conducting the meeting.
Hertfordshire is a county in the southeast of England. Home to the Bennets, it is the setting for most of Pride and Prejudice.
Girls belonging to the upper classes spent most of their time learning skills or accomplishments that would theoretically help them attract a husband, and which were therefore often neglected after the wedding.
An accomplished girl might have learnt to draw, sing, play music and speak foreign languages.
The numbers Mrs Bennet mentions refer to sets of English country dances. The Boulanger was an easy dance, derived from the Cotillion, which allowed every lady to dance briefly with every gentleman.
The fictional town of Meryton in Hertfordshire was probably inspired by Hertford.
The building, which still stands, ceased to be used as a royal residence not long after the death of Jane Austen.
A hack chaise is a carriage for hire, like a taxi, used by those without the means to keep their own carriage. It is presumed that Mr Darcy would not want to talk to Mrs Long if he knew she used that mode of transportation.
Vingt-un or Vingt-et-un is the French version of what became Blackjack, with a few alterations. Vingt-et-un, French for twenty-one, originated at the beginning of the 18th century in French casinos.
Commerce, on the other hand, was invented a century later, also in France. It is similar to Vingt-un, so the comment regarding which Jane and Mister Bingley both like best shows how little they know one another yet. This is, of course, the point of the comment made by Elizabeth.