Internet memes are considered in the article as a new kind of informal mass communication. The authors substantiates the admissibility of determining their essence based on the use of three basic categories (phrases, images and their combinations) and three distinctive criteria (creation by means of computer technologies, distribution mainly on the Internet, and actualization of emotional attitude to objects of the external or internal world). Two common methodological errors of researchers of network creativity products are described: the tendency to consider Internet memes by themselves, in artificial isolation from other phenomena, and the trend of endowing Internet memes as a whole with the characteristics of their particular varieties. The typology of Internet memes is clarified, based on the use of parameters of the form of presentation to the audience, subjective ideas about authorship, subject matter and modality of emotional attitude to the received materials. It is proposed to revise the existing lists of social functions of Internet memes based on their belonging to informal mass communications. At the same time, the functions common to the manifestations of the phenomenon (expressive, stereotyping, self-presentation, relaxing) and specific, additional, implemented in certain thematic varieties of Internet memes are distinguished. In particular, for those related to political issues, this is primarily a manipulative function, for news - informational, for those used in education - didactic, for marketing - voluntary, for those spreading in the context of social conflicts - identifying, for reflecting feelings of personal distress creators - therapeutic and so on. The article argues that further study of Internet memes in the paradigm of informal mass communications will create prerequisites not only for monitoring public opinion, but also help in countering content aimed at whipping up social discord and tension.