There are a lot of Arabic-speaking countries each with its own variety of an Arabic dialect with a Modern Standard Arabic (MSA or "fusha""Fusha") being the language of the media and official speech, and Classical Arabic being the language of the Quran.
Would I be understood and is it normal to speak Modern Standard Arabic in the Arabic-speaking countries or do I need to study the dialect of the country where I am traveling to? Is the situation different for North African countries vs countries of the Gulf?