Although nowadays you may be able to get yourself in and out of trouble just by knowing English, the degree of which you will do will vary from place to place! Fortunately, In Iran, you will not be able to get yourself into much trouble by only knowing English. However if you wish to get a much fuller experience, which means communicating and mingling with the locals, it will be quite to your advantage to know a few key words and expressions. GoingIRAN has put together the following chart to help travellers along their journey in Iran.
There are 15 different languages and even more different dialects all across Iran; the most useful and most commonly used one is Farsi (Persian). While it is true that when out shopping or visiting tourist attractions there will be people that can help you out that know English, it is not always the case! Most taxi drivers and some shop owners and restaurant servers may not know a word of English or any other language other than Farsi.