Udi is spoken by less than 9.000 people. More than 4.000 speakers live in northern Azerbaijan. The rest of them live in Georgia, Russia, and Turkmenistan.
Udi belongs to the Lezgian subgroup of the Northeast Caucasian language family.
Main dialects are Oghuz/Vartashen, Nidzh (in Azerbaijan), and Oktomberi (in Georgia).
The speakers call their language udi muz.
Udi is written with Cyrillic letters.
The Udi sound system comprises 35 consonant phonemes (with a threeway opposition: voiced, voiceless, glottalised) and 16 vowel phonemes (including three palatalised and six pharyngealised vowels).
Udi morphology is largely agglutinative with some fusional tendencies. The noun has 11 cases. The inflectional paradigm of the noun is divided between functional cases (ergative, genitive) and locative cases (comitative, superssive, allative, adessive). As a rule case marking is ergative: subjects of intransitive verbs and direct objects are zero-marked (by the absolutive case) and subjects of transitive verbs are marked by the ergative case. Nevertheless, there are some deviations from this rule. Udi has no noun classes.
The formation of the Udi verb is strictly agglutinative. Suffixes express the categories tense, aspect, and mood. Verb agreement is accomplished by free clitics and follows an accusative pattern: regardless of its valency the verb agrees with the subject.
The preferred word order is SOV. The possessor (marked by genitive case) precedes the possessed noun. The adjective usually precedes the qualified noun. Udi uses postpositions to express local meanings.