Downton Abbey was produced for six seasons. The British series aired from 2010 to 2015 and followed the aristocratic Crawley family and their servants through the social changes of the early 20th century.
Each season is called a “series” in British television usage. Across the six series, Downton Abbey broadcast 52 episodes, including the popular Christmas specials that extended several seasons beyond their regular episode runs. The sixth series was confirmed as the final one and concluded with a Christmas episode in December 2015.
The number can be confusing because streaming services sometimes split Christmas specials into two parts, which can make the episode total appear higher. That does not mean there were more than six seasons. The series later continued in feature films, beginning with Downton Abbey in 2019, but those films are separate from the original television run.