1. The main characters were actually morally ambiguous.

While sitcoms usually try to paint good and evil as black and white, "Seinfeld's" main cast was actually morally ambiguous. They usually did things for their own gain or used illnesses and disabilities to get out of commitments. This usually snowballed into something more and created more problems that they were trying to avoid, thus driving the plot of the episode. A good example of this is when Elaine pretended to be deaf so she didn't have to talk to her driver in the episode "The Lip-Reader."

2. Nothing was ever resolved.

While sitcoms usually try to resolve the plot by the end of the episode, "Seinfeld's" episodes usually ended with the conflict being unresolved or worsened by character's actions. This, I believe, gave the series a darker tone since we didn't know how the characters get out of their current predicament which leaves it up to the imagination of the viewer. The best episode to view this would be "The Chinese Restaurant," where George, Jerry, and Elaine are waiting for a table at a Chinese restaurant, only to give up by the end of the episode...and the host calls out their name.

3. There was no "Will They or Won't They" between Jerry and Elaine.

While sitcoms usually drag on a romantic sub-plot between two characters for multiple seasons (ahem, Ross and Rachel), "Seinfeld" threw that trope out the window. In the series, it is established that Jerry and Elaine were a couple before they were friends, thus establishing their connection. However, they stay friends throughout the run of the series and don't give in to the "Will They or Won't They" narrative. However, in the episode "The Mango," Jerry and Elaine do have sex again only because Jerry found out that Elaine had faked some of her orgasms while they were together, and he wanted to try and make her orgasm for real.

4. The reoccurring characters were better than the principles.

"Seinfeld" wouldn't be "Seinfeld" if it weren't for it's colorful cast of reoccurring characters. Characters like Newman, Uncle Leo, Frank and Estelle Costanza, and J. Peterman added to the wackiness of the plot lines used in the series. Larry David based a lot of his characters off of people he knew while living as a comedian in New York, adding to the realism of the show.

5. Some "Seinfeld" lines have become everyday phrases.

Have you ever caught yourself saying "Yadda Yadda" or "Not that there's anything wrong with that"? That's because "Seinfeld" originated them. Phrases like "Sponge-worthy" and "No soup for you!" have become so ingrained within the American lexicon that not everyone knows where they came from. Some "Seinfeld" phrases have even become a part of the dictionary, contributing to the show's iconic longevity.