This article gives an overview of the main research questions and findings unique to audiovisual speech perception research, and discusses what general questions about speech perception and cognition the research in this field can answer. The influence of a second perceptual source in audiovisual speech perception compared to auditory speech perception immediately necessitates the question of how the information from the different perceptual sources is used to reach the best overall decision. The article explores how our understanding of speech benefits from having the speaker's face present, and how this benefit makes transparent the nature of speech perception and word recognition. Modern communication methods such as Voice over Internet Protocol find a wide acceptance, but people are reluctant to forfeit face-to-face communication. The article also considers the role of visual speech as a language-learning tool in multimodal training, information and information processing in audiovisual speech perception, lexicon and word recognition, facial information for speech perception, and theories of audiovisual speech perception.