When Greys Anatomy fan Seyward Darby says she keeps up with new episodes of the long-running medical drama, people look at me sideways, she said.

As a fellow fan, I often hear a similar sense of disbelief: I cant believe you still watch that show.

But were not alone. Greys Anatomy is still one of the most-watched dramas on network television, and Thursday marks the beginning of its 20 th season (seriouslyseriously seriously!).

After 420 episodes and almost two decades on the air, the legacy of Greys Anatomy and its effect on pop culture has been long discussed. It diversified casts. It attracted people to the medical field. It celebrated women for being ambitious and complicated and for having good sex. It drew attention to social and political issues , such as gay rights and gun violence (sometimes imperfectly) that other shows often avoided completely. It launched the careers of creator Shonda Rhimes and original cast members Ellen Pompeo, Chandra Wilson , Katherine Heigl and Sandra Oh (and many other actors, writers and producers affiliated with the show).

It also became the longest-running prime-time medical drama on television, outlasting more characters than I can name, both of its spinoffs (Private Practice and now Station 19, which was just canceled), multiple showrunners (Meg Marinis is succeeding Krista Vernoff) and its titular lead character (Pompeo departed the show as a series regular last season ).