As the longest-running primetime medical drama series, Grey's Anatomy has kept millions of fans hooked over the years. Released in 2005, the series follows the lives of surgical doctors at a hospital who deal with tense emergencies and the passionate highs and lows of workplace romances. Few shows can last so long without getting boring or repetitive, but there's a reason whyGrey's Anatomy has gone on for 21 seasons, with Season 22 on the way.