The official language which is spoken in Iran is Persian. Actually, over 60% of the population speak Persian, but, no need to know Persian to travel to Iran as most of the people know English although they can’ not speak fluently.
As Iran is a multicultural country so there are some other languages that people talk in some specific regions such as Turkish, Kurdish, Luri, Arabic, Balochi and Gilaki.
Also, there are many different dialects in different parts of Iran which you will meet while traveling in Iran but the main language for government, industry, and school is Persian.
The Persian language is so famous in music, poetry, and art that you can see many Persian masterpieces around the world.