Ljig is situated in the western part of Central Serbia, at 152m altitude. It is announced as a town in 1922, and now is administrative and economic centre of Ljig municipality.

Ljig covers an area of 279 square kilometres, comprising of 26 settlements: Ba, Babajic, Belanovica, Bosnjanović, Brancic, Velisevac, Gukos, Dici, Donji Banjani, Zivkovci, Ivanovci, Jajcic, Kadina Luka, Kalanjevci, Kozelj, Lalinci, Latkovic, Liplje, Ljig, Moravci, Paleznica, Poljanice, Slavkovica, Cvetanovac, Štavica and Šutci.

The town is named after the river holding the same name. The Ljig River splits the municipality area on two administrative parts: Sumadia and Kolubara.

According to the census from 2002, there are 14629 inhabitants. Based on the criterion of area surface and population, Ljig belongs to the group of small municipalities.