Grey's Anatomy is an American medical drama television series that premiered on March 27, 2005, on ABC as a mid-season replacement. The series focuses on the lives of surgical interns, residents, and attendings as they develop into seasoned doctors while balancing personal and professional relationships. The title is an allusion to Gray's Anatomy, a classic human anatomy textbook first published in 1858 in London and written by Henry Gray. Shonda Rhimes developed the pilot and continued to write for the series until 2015. Krista Vernoff, who previously worked with Rhimes, is now the showrunner. Rhimes was also one of the executive producers alongside Betsy Beers, Mark Gordon, Krista Vernoff, Rob Corn, Mark Wilding, Allan Heinberg, and Ellen Pompeo. Although the series is set in Seattle, Washington, it is filmed primarily in Los Angeles, California, and Vancouver, British Columbia. The series revolves around Ellen Pompeo's character, Dr. Meredith Grey, until halfway through its 19th season, after which it shifts to a more ensemble format, with Pompeo only appearing in 8 episodes of season 19. Grey is first featured as an intern and later becomes the chief of general surgery while showcasing the complications of a surgeon's life. The original cast consisted of nine star-billed actors: Pompeo, Sandra Oh, Katherine Heigl, Justin Chambers, T. R. Knight, Chandra Wilson, James Pickens Jr., Isaiah Washington, and Patrick Dempsey. The cast has undergone major changes throughout the series' run. At the start of the 19th season, the show had a large ensemble of 17 actors—including three from the original cast (Pompeo, Wilson, and Pickens). Grey's Anatomy is the longest-running scripted primetime show currently airing on ABC, and the longest scripted primetime series carried by ABC. Its success catapulted many longtime series regulars including Pompeo, Dempsey, and Oh to worldwide recognition; they were among the top five highest-earning television actors in 2013. While the show's ratings have fallen over the course of its run (it was once among the overall top-ten shows in the United States), it is still one of the highest-rated shows among the 18–49 demographic, and the #3 drama on all of broadcast television in the United States. The series was the highest revenue-earning show on television in terms of advertising in the 2007–08 season; in 2017, it was ranked tenth on the list. In its 15th season, Grey's Anatomy ranked as ABC's highest-rated drama. As of February 28, 2019, it was the