Arabic belongs to the Semitic family of languages. Besides Arabic, spoken languages in this family include Modern Hebrew, Amharic, Tigre, Tigrinya, Syriac, a few Aramaic dialects, and Maltese. 250 million people in the Arab world speak Arabic as their native language. Furthermore, 1.2 billion Muslims all over the world use Arabic in their prayers and religious recitations. Arabic is also the liturgical language of many Eastern Christian churches.
For practical purposes, we may divide Arabic into three varieties:
Classical Arabic is the oldest type of Arabic that is studied widely. It is the language of the Qurʾān and texts from the classical age of the Islamic empire (including texts dealing with Qurʾānic subjects), the ḥadīth, Islamic law and theology, history, biography, geography, poetry, grammar, medicine, and other sciences. Until a few decades ago, this was the type of Arabic most commonly taught in universities. Classical Arabic is still used today, but is restricted to religious and highly formal contexts.
Modern Standard Arabic (MSA) or al-Fusḥa is a direct descendant of Classical Arabic and is now the language of elevated discourse or correspondence, contemporary literature, and the mass media (whether newspaper, radio, television, or the internet). MSA is a formal, mainly written language that is not used for daily-life communications. There are no native speakers of Modern Standard Arabic, but the vast majority of the educated in the Arab world learn MSA through formal schooling. Although Arabs not educated formally cannot produce MSA, many can comprehend it because of the considerable overlap between the different varieties of Arabic. Modern Standard Arabic remains largely uniform throughout the Arab world.
Colloquial Arabic, or ʿAmmiyya, refers to the regional dialects used in everyday discourse and popular culture media. There are numerous dialects in the Arab world that vary along geographical, socio-economic, and religious lines. Arabs from one region can generally understand dialects from other regions, depending on proximity, exposure to other Arab dialects, education and command of MSA.
In general, there are four major dialect groups in the Arab world today:
(1) The Maghrib (Morocco, Mauritania, Algeria, and Tunisia)
(2) Libya and Egypt
(3) The Levant (Syria, Lebanon, Jordan, Palestine, and parts of Iraq)
(4) The Gulf Area (Saudi Arabia, Yemen, UAE, Kuwait, Oman, Bahrain, Qatar).
To become fluent in Arabic, you need to develop proficiency in MSA and one of the dialects. Your choice of which dialect to study depends on your goals.