The term, however, is more philologically valid than anything else and has almost no true racial value. As Indic, Iranian, and most European languages (with the exception of Hungarian, Finnish, Estonian, and Basque) display morphological and phonological, as well as grammatic similarities, it has been theorized that they all form a single language family, called "Indo-European" by scholars. These also include the now extinct languages of Tocharian and Anatolian languages such as Hittite and Lycian. Armenian is also an independent branch of Indo-European.
It should be noted that not all languages of India and Iran are part of this language family. In India, the Dravidian language family (which includes Tamil, Telegu, and Kannada) are not Indo-European. In Iran, Turkish (Ural-Altan) and Arabic (Semitic), as well as Brahui (Dravidian) are not part of the language family. Outside the boundaries of Iran and India, languages such as Urdu, Pashto, Tajiki Persian, Ossetic (spoken in Russian and Georgian Ossetia) and many other minor languages of Afghanistan and even western China are part of this family of languages. Also, as a consequence of European colonialism, Indo-European languages have broken out of the boundaries of Europe into the New World and other continents. At present, Indo-European is the largest language family on earth.
Aside from language, the scholarship on Indo-European has also concentrated on mythology. Similarities between the mythological beliefs and premitive religions, including appearance of similar figures and myth cycles have lead most scholars to believe that these beliefs, like the languages, have their origin in a common source.
Much of the Indo-European archaeology has concentrated on the issue of immigration of the Indo-European people in the late Stone Age and early Bronze Age. It particularly has concerned itself with the issue of locating an original Indo-European population, as well as their "Homeland" (often known with the German title "Urheimat").
The IE root *dheu- also results in words relating to god and divinities in most "daughter" languages: Lat. deus , Gk. Zeus, Avestan dew- (evil spirit) and Skt. deva-