How is the Albanian language related to the Indo-European language family?

Albanian is a distinct member of the Indo-European language family, serving as the sole modern survivor of its own unique branch. Its status as an Indo-European language was formally recognized by the philologist Franz Bopp in 1854, with further linguistic evidence established by scholars such as Gustav Meyer, Holger Pedersen, and Norbert Jokl.1

While Albanian clearly belongs to the Indo-European family, it does not show a close affinity to any other specific branch. It is believed to be the descendant of an ancient, poorly attested language from the Balkan Peninsula, with Illyrian and Dacian being tentatively considered as potential ancestors or close relatives. Linguists have also suggested that the Balto-Slavic group may have been its nearest kin in very early times. Despite significant phonetic changes and extensive vocabulary borrowing from neighboring cultures over the last 2,000 years, the language retains archaic Indo-European traits, such as specific verb endings and stem vowel alternations.21