Anantnag (Urdu pronunciation: [ənənt̪nɑːɡ] ; Kashmiri pronunciation: [anant̪naːɡ] listen^ⓘ), also called Islamabad (Urdu pronunciation: [ɪslɑːmɑːbɑːd̪] ; Kashmiri pronunciation: [islaːmaːbaːd̪]), is the administrative headquarters of Anantnag district of Indian-administered Jammu and Kashmir in the disputed Kashmir region. It is located at a distance of 53 kilometres (33 miles) from the union territory's capital Srinagar. It is the third largest city in Jammu and Kashmir after Srinagar and Jammu with an urban agglomerate population of 159,838 and a municipal limit population of 109,433.

The town has been called by both the names Islamabad and Anantnag. The latter is characterised by Marc Aurel Stein as its "Hindu name".

"Anantnag" derives from the name of the spring at the southern end of the town, whose Sanskrit name Anantanāga was mentioned in the Nilamata Purana and other texts. According to the Gazetteer of Kashmir and Ladak, it is named after Ananta, the great serpent of Vishnu and the emblem of eternity.

The name Islamabad is believed to have derived from the name of a Mughal governor Islam Khan who built a garden in the area.

Both names are used for the town, Anantnag being preferred by the Hindus and Sikhs while Islamabad is preferred by the Muslims. The locals continue to use the name Islamabad, even though the Indian security forces deployed in the area from 1998 onwards frown on its use.

During the Dogra rule, Anantnag/Islamabad was the headquarters of one of Kashmir Valley's three districts, which was referred to as the "Anantnag wazarat".

Anantnag is located at 33°44′N 75°09′E / 33.73°N 75.15°E / 33.73; 75.15, at an elevation of 5,300 feet (1,600 m) above sea level, at a distance of 53 kilometres (33 mi) from Srinagar on NH 44 (former name NH 1A before renumbering of all national highways).

There are three definitions of Anantnag: