According to the Greek mythological legend, Tilos was the son of Alia and Apollo (the Sun God) went to the island to collect therapeutic herbs for his mother when she was seriously ill. After Alia’s recovery, Tilos expressed his gratitude by constructing a sanctuary in honor of Apollo and Poseidon. The island was named after him and for a long time after, it was well known for its curative rare plants and herbs.
Findings in Charkadio cave, such as Neolithic stone tools and fragments of pottery from the Neolithic Era and early Copper Era prove the human presence on the island. Archaeological findings from the early Copper Era were collected from Lakkes and conical Minoan cups were found south of Megalo Horio.
Findings in Kastellos (Livadia) reveal the Minoan presence during 1600 BC and Mycenaean and Dorian presence, during the 13th-12th century BC. Pirate invasions till the 8th century led to the decadence of the settlers of the island.
It was during the Classical period that Tilos reached the peak of economic and cultural prosperity.
The island was particularly famous for perfume production and also for the poet Irinna (5th century BC) who was considered as talented as Sappho. 
The ancient cemetery of St. Antonios, the graves in Plaka, the remnants of a tower in Livadia and other fortifications reveal the Classical and Hellenistic history of Tilos.
In the 5th century BC, Tilos became part of the Athenian confederacy and remained dependent upon the island of Rhodes, until it passed to the Romans. The diversity of archaeological findings from the Paleochristian period bears witness to the island’s prosperity that lasted till the earthquake of 550 AD.
The most important Byzantine castles are the Paliokastro situated at Mikro Horio, the castle of St. Stefanos in Livadia and the one in Megalo Horio that was reconstructed during the dominance of the Knights of St. John.
In 1366, Tilos passed as a benefice to Barrelo Assanti d’Ischia, in 1522 it was invaded by the Turks along with all the Dodecanese and in 1912 it was conquered by the Italians. It was in March of 1948 that Tilos was liberated and integrated into the Greek State. 
Tilos is one of the smallest islands in the Dodecanese, the seventh in declining area. It is located 22 miles NW of Rhodes and 222 miles from Piraeus.
It has an irregular shape and its area is 61,487 Km2, Intense relief and lacy beaches, while its population is 780 inhabitants.
It is surrounded by 16 islets and the small island of Antitilos is found about 2 miles away.
The main settlements of the island are Megalo Chorio being the biggest village, Livadia the island’s port, Eristos, a fertile valley leading to the island’s most beautiful beach and St Antonios whereby Nisiros and Kos can be seen. 
The land of the island is mountainous and rocky with a small plain in the center that ends at the beach of Eristos, where four hundred species of flowers and herbs germinate, inhabited by numerous species of rare birds (Bonelli’s eagle, hawks, nightingales, goldfinches, herons, bee-eaters etc). 
Tilos has springs and an artificial lake fed by the surface run-off of the torrent Potamos, thus in its territory citrus trees and vegetables are cultivated.
The highest peak is Profitis Ilias with an altitude of about 620 meters. The total development of the island's shores reaches 63 km.
The whole island is a huge ecological park and is protected by international conditions.
The climate of the island is Mediterranean, with mild winters and cool summers.
The inhabitants of the island are engaged in fishing, agriculture, beekeeping and tourism.