The Kakadu region is culturally diverse. The Aboriginal people in the region are from a number of different clans, often speaking different languages and in some cases upholding different traditions.
A clan usually consists of two or more family groups that share an area of land over which they have ownership. Clan boundaries are passed from one generation to the next, generally through the father. Before the arrival of non-Aboriginal people there were over 20 clan groups in the Kakadu area; now about 19 remain.
The kinship system of the Aboriginal people in the Kakadu area is very complex. All people, plants, animals, songs, dances, ceremonies and land are divided into two groups, or 'moieties': Duwa or Yirridja. Each moiety is subdivided into eight 'skin' groups. A child's skin group is determined by their mother's skin group but they inherit their moiety from their father.
In simple terms, kinship can be described as a system that defines how people relate to each other. Through the use of 'skin' names people identify others around them as mothers, fathers, uncles, aunts, cousins, potential marriage partners, and so on, and modify their behaviour accordingly. Almost every aspect of day-to-day communication with other Aboriginal people is governed by kinship ties.
The Warradjan Aboriginal Cultural Centre houses a very good display and interactive game that will help you understand kinship.
At the time of non-Aboriginal settlement 12 languages were spoken in the Kakadu area. Today only three are spoken on a regular basis: Gun-djeihmi, Kunwinjku and Jawoyn. Many Aboriginal people still, however, speak two or more languages, often a consequence of spending time with relatives who belong to a different clan and language group. Aboriginal English, with its own grammatical rules, is a recognised dialect of English and is also widely spoken. Most of the quotes from Aboriginal people in this web site are in Aboriginal English.
Unlike English, the spelling system used to record local Aboriginal languages is very consistent. So once you have learnt the alphabet, it is quite easy to pronounce words by sounding them out. The Aboriginal Language factsheet details the Gun-djeihmi alphabet.