The word prep comes from the word preparatory, meaning a preparatory school. True preps are totally not mainstream and they have an original style. They wouldn't dare shop at Abercrombie, Hollister, Aeropostale, etc..
Rather, they shop at stores like J Crew, Polo Ralph Lauren, Vineyard Vines, Lilly Pullitzer, and Small Boutiques. They take pride in their academics and usually end up in an ivy-leauge college. Most preps are very athletic, well-groomed, and carry themselves well. Despite what others say on this website, Preps usually have one or a few extreme talents that they work on hard, and are usually very creative. They do come from money. However, It is usually old money that has been past down by generations of preps. Preps don't usually flaunt their money. They are very conservative. The basic definition of preps is- classy people who have an original style and carry themselves well.
I really have no clue where people get the idea that preps are mainstream.
Non-Prep- "How would you describe yourself?"
Prep- "I'm preppy"
Non-Prep- "So you shop at abercrombie and aeropostale?"
Prep- "Are you serious? Of course not! Real preps would never shop there"