Indo-Germanic Languages are a group of languages which originated in India and Iran. Most of the European languages are included (except the Finno-Ugric and Basque languages). The principal branches from this common origin are: Germanic, Baltic, Celtic, Italic, Greek, Slavic, Iranian and Indic. The entire body of Aryan or Indo-Germanic languages is derived originally from monosyllabic elements. There are two classes, verbal and pronominal. These two grammatical forms combined, gradually formed the rudiments of vocabulary and grammar.
The framework of the languages in all the different branches is practically the same.
Based on : The Concise Encyclopedia, A Library Of World Knowledge,Ed. by A.H. McDannald, B.L., Editor-in-Chief, The Encyclopedia Americana 1933