What criteria define being middle class?

[Unit1]

Is it the Salary, that defines middle class? I heard its minimum $3000 per month and you'll be considered middle class. Although i am not sure if it's gross salary or after the taxes.

[Anonymous]

Dont know about how much money youd need, but I think it is also the attitude that defines social class... if you give someone who normal has nothing a lot of money, they won't necessarily become upper middle class, but they will be a rich but sort of in their class.
E. g. if someone wins the lottery, and spends all their money in a matter of months, they never had the mindset of a middle class individual... as part of the mindset is looking at what you have, and working out how to secure yourself properly and make the most out of what you have... at least this is how I was taught it