Norms for audiovisual translation (AVT) regulate the ways in which AVT is carried out. These norms develop over time in response to developments in society and technology, and vary in strength from idiosyncrasies to rules. Norms can be either explicit and codified, as those found in guidelines and textbooks, or implicit and based on translation practice. Descriptive research is carried out in order to uncover the latter kind of norms. Guidelines are used to introduce newcomers to AVT, as reference works, and as standards for quality assessment. Currently, a new global prescriptive set of norms are challenging old local norms, while at the same time, traditional norms are challenged by experimental and cognitive research into what viewers really prefer.