Tripolitania (today a part of Libya) is an area located next to the Mediterranean sea. It was controlled by Italy after the defeat of the Ottoman Empire during the Italo-Turkish War of 1911-1912. During the period of Italian control, stamps used in Tripolitania were Italian definitive stamps with overprints ("Tripoli di Barberia" until 1923, when the "Tripolitania" overprint was first used). The first stamps, overprinted "Tripolitania" on the Italian "Propogation of Faith" series, are pictured below. In 1926, Tripolitania began issuing its own stamps (as part of the colonial issues of Italy), which is pictured below, in addition to using the overprinted Italian definitives.   

Stamps issued on October 24th, 1923, the first stamps to be overprinted with "Tripolitania"

Another Italian colony, Cyrenacia, also issued these definitives on this day, and they are considered to be the first stamps of the colony. Five days after the stamps were released, another set was issued, once again using Italian definitives. 

Stamps issued on October 29th, 1923. 

The watermark on all of the stamps of Tripolitania is the same as on the definitive issues of Italy.

1926 Colonial Issue

Used stamps are worth around twice as much as unused ones, with fake cancels often being found.The Italian Government Printing Works made all of the stamps used in Tripolitania. Although Tripolitania continued to issue its own postage stamps until 1938. It became a part of Libya in 1939, along with other Italian colonies of Cyrenacia and Fezzan, with the supervision of the Italian governor-general.