Referred to any feature that a company or entrepreneurial organization uses to greatly promote their product as a way to catch the attention of the customer.
Note that selling points don't always mean the product is good, as some companies tend to force selling points that wouldn't bring any benefit or generate any interest in the potential customer.
Jack: Hey, did you see that new Black Ops 4 trailer? It's so cool!
Kevin: Yeah, I saw it. Honestly, I don't like how the studio is using the "Battle Royale" feature as their selling point.
"This cute guy asked me out, I wasn't gonna go due to Hair Migration, but then he sent a vid of his puppy."
"So... the puppy was the selling point?"
"Yeah. I guess the guy'ssurplus, but I'm such a sucker for dogs."
