Premodernist

The country of Iran used to be called Persia. Who changed its name and why? Also is the language of Iran Persian or Farsi? Is it okay to say "Persian"? Where do the words "Persian" and "Farsi" come from?

I answer all these questions in this video.

EDIT: Many Iranians are discovering this video (Welcome! Khosh amadid!), and some are upset by what I say here. I recommend they read this piece by Ehsan Yarshater, a distinguished scholar of Persian/Iranian history:
https://web.archive.org/web/20160714205848/http://www.iran-heritage.org/interestgroups/language-article5.htm

N.B.: Don't think that because some Iranians/Persians in the comments are objecting to the terms "Persia" and "Persian", that that represents all people of Iran or of Persian culture. Many Persians would prefer that Westerners use the term "Persian." Some prominent ones are named in the short article linked above, and I have also known Persians in my daily life who expressed this view. When Reza Shah issued that request to foreign governments in 1934, he created an unnecessary complication that makes it more difficult for foreigners to get to know and understand the Persian people.

Sources for my claim that Reza Shah's request was a 'marketing gimmick':

"The most visible name change came in 1934 when Reza Shah -- prompted by his legation in Berlin -- decreed that henceforth Persia was to be known to the outside world as Iran. A government circular explained that whereas "Persia" was associated with Fars and Qajar decadence, "Iran" invoked the glories and birthplace of the ancient Aryans."
Ervand Abrahamian, A History of Modern Iran (Cambridge, 2009), page 86

"In terms of foreign policy, Reza Shah was determined to maintain Iran's independence and to restore its sense of national pride by elevating its stature in the world and insisting it be treated with respect. This was the motivation behind any number of his actions, from insisting on the use of the name Iran instead of Persia to banning photographs of things that were picturesque but might give an impression of backwardness (camels, for example) to breaking off diplomatic relations with countries if its newspapers published unflattering articles about him or his country."
Elton L. Daniel, The History of Iran (Greenwood Press, 2001), pages 139-140