The subject of the thesis is the communication on the microblogging platform Twitter, which has in the recent decades become one of the leading social networks for the exchange of personal and often politically motivated content. The thesis aims to explore for what communicative purposes the internet users communicate with the public through tweets, as well as what is the role of different modalities (such as language, typography, image, video etc.) and forms of intertextual or intermedia networking. To explore this, the thesis examined selected tweets in German concerning their functions, topics, linguistic features and other semiotic resources, as well as various aspects of intertextuality. With its findings, the thesis contributes to the study of Twitter communication from a usage-oriented perspective.