Arabic (اَلْعَرَبِيَّةُ, al-ʿarabiyyah [al ʕaraˈbijːa] (listen); عَرَبِيّ, ʿarabīy [ˈʕarabiː] (listen) or [ʕaraˈbij]) is a Semitic language spoken primarily across the Arab world. Having emerged in the 1st century, it is named after the Arab people; the term "Arab" was initially used to describe those living in the Arabian Peninsula, as perceived by geographers from ancient Greece.

Since the 7th century, Arabic has been characterized by diglossia, with an opposition between a standard prestige language—i.e. Literary Arabic: Modern Standard Arabic (MSA) or Classical Arabic—and diverse vernacular varieties, which serve as mother tongues. Colloquial dialects vary significantly from MSA, impeding mutual intelligibility. MSA is only acquired through formal education and is not spoken natively. It is the language of literature, official documents, and formal written media. In spoken form, MSA is used in formal contexts, news bulletins and for prayers. This variety is the lingua franca of the Arab world and the liturgical language of Islam. It is an official language of 26 states and 1 disputed territory, the third most after English and French. It is also one of six official languages of the United Nations.

Spoken varieties are the usual medium of communication in all other domains. They are not standardized and vary significantly, some of them being mutually unintelligible. The International Organization for Standardization assigns language codes to 33 varieties of Arabic, including MSA. Arabic vernaculars do not descend from MSA or Classical Arabic. Combined, Arabic dialects have 362 million native speakers, while MSA is spoken by 274 million L2 speakers, making it the sixth most spoken language in the world.

Arabic is traditionally written with the Arabic alphabet, a right-to-left abjad. This alphabet is the official script for MSA. Colloquial varieties were traditionally not written, however, with the emergence of social media, the amount of written dialects has significantly increased online. Besides the Arabic alphabet, dialects are also often written in Latin from left to right or in Hebrew characters (in Israel) with no standardized orthography. Maltese is the only colloquial variety officially written in a Latin alphabet.