When Grey's Anatomy began airing as a mid-season pickup in March 2005, no one could have predicted how quickly the show would rise to national and international acclaim. Audiences immediately enjoyed watching the five main interns navigate their first year in medicine, and the show became known for its dramatic storylines, incredible soundtrack, and big speeches. With a cast of mostly unknown actors, Patrick Dempsey as Dr. Derek Shepherd was the initial draw for many viewers, but it was his relationship with Meredith Grey (Ellen Pompeo) and the dynamic friendships (and rivalries!) that kept people coming back.
Source：https://www.cbr.com/greys-anatomy-everything-to-know-season-20/
