Intersyst has two official languages that it uses: Universal Phonetic and Universal Ideographic, however in practice Universal Phonetic is the only one that is used with Universal Ideographic being kept on reserve while the idea of switching to it as the main language has been kicked around for decades. The Intersyst Education Standardization Institute requires that all students in member systems learn Universal Phonetic in primary and secondary school. Beyond that the languages that each citizen learns is dependent on which Federation they are a part of. In the Human Federation, the average citizen is trilingual, learning their system language, the Human Consolidated Language, and Universal Phonetic. Citizens of the Purian Confederation will learn four to five languages: Universal Phonetic, Imperial Hyperian, their local system language, their planetary language, and their local regional language if it exists. Citizens of the Youmen United Systems usually are proficient in 5 or more languages thanks to their highly developed linguistic faculties, learning the Youmen Unified Language, which is the same across all systems save for dialectal differences, Universal Phonetic, Universal Ideographic, Human Consolidated, and Imperial Hyperian.
It is now known that the reason for the differences in language diversity is not driven by language formation but rather by language preservation. During colonization, different nations colonized their own systems. For the humans, the languages of those nations live on as the system languages. After the second wave of colonization, the Human Federation created the Human Consolidated Language to streamline federal operations. For the Youmen, all languages were replaced by the Youmen Unified Language shortly after colonization began. For the Purians, the different nations that went and colonized their respective systems each had a national language but also several regional languages. Within each colonized system, the members of each subnational region spread out across the different planets available within each system. On systems where there were not enough colonizable planets, the different regional languages and the national language persisted as the local regional languages and planetary language, respectively. For the purposes of communicating between regions or systems, Imperial Hyperian is generally accepted as the de facto common language and is taught in all purian schools with the exception of a few Nycean systems.