Abstract: The article discusses the issue of aggressiveness and courtesy when communicating on the Internet, in particular at the forum of the Russian-speaking population of Finland. The definitions of linguistic expression and aggressive linguistic expression are given. A review of studies on the aggressiveness of communication on the Internet. It is noted that the term aggression refers rather to the sphere of other humanities, while the concept of aggressive language expression is more applicable in linguistic analysis and, as well as the method of analysis of language expression is developed. Attention is paid to the categories of politeness in communicating on the forum, pragmatic characteristics of communication are considered. Presents the results of the analysis of dialogues on the forum. The question is also raised about the applicability of the binary opposition of sociolinguistics “our own” - “alien” to the consideration of communication on the forum. Special attention is paid to foreign elements from the Finnish language when communicating in their native (Russian) language among the Russian diaspora. The novelty of the study is caused by the fact that verbal means of language expression are analyzed when communicating with the Russian diaspora. The relevance of the study is due to the increased interest among both linguists and society to the new role of the Russian language as a world language abroad and in the post-Soviet space, as well as its role as the language of the diaspora. The definitions of language expression and aggressive language expression are given. The author dwells on those types of language expression, which form the language communication on the forum. It is proved that politeness is a response to the aggressiveness of communication.