This chapter discusses defences that exempt certain activities from infringement on the basis of their transient or incidental character. These tend to be of paramount importance in cases of electronic communications and, more specifically, on the Internet as a result of the very nature and function of online networks. The exception available for temporary copying, for instance, which features in Article 5(1) of the Information Society Directive, has specifically been drafted with a view to covering online activities, such as caching and browsing, that enhance the efficiency of the Internet. Subject to discussion is the temporary copying exception in its broader contextual framework, including the relevant statutory provisions and case law, such as Infopaq I and II, Football Association Premier League, Meltwater, and Filmspeler decisions. It is argued that although Article 5(1) of the Information Society Directive takes, organically, the form of a copyright exception, the relevant provision should be better understood to be setting a scope limitation on the reproduction right and an exemption from copyright infringement.