The article presents a lexicometric and factorial research in which we analyze the most relevant linguistic and paralinguistic characteristics of Spanish teenagers' digital writing in one of the most popular and used instant messaging programs (WhatsApp©). Writing in digital mobile devices (smartphones and tablets) is one of the most commonly activities in our society and is an essential component of communicative competence in the Information and Communication Society. Digital communication is part of our lives and the analysis of the use of digital and ubiquitous communication devices and programs has a broad social, language, and teaching impact. The research has been contextualized in four Spanish provinces with a sample of 417 WhatsApp digital chats among high school students aged from 13 to 16. A quantitative methodology has been implemented from a lexicometric approach in order to analyze the digital linguistic corpus with reference to the most relevant linguistic and paralinguistic elements. Therefore, we have established correlations between independent variables that could explain digital writing linguistic patterns and usage. The results show that digital writing in this instant messaging app has special orthotypographic and audiovisual characteristics conditioned by usage variables such as size of the device display, hours of conversation, and relationship between speakers.