Cyberspace, the internet and vituality are widely understood in terms of poststructuralist or antiessentialist expectations that when identity is separated from physical bodies it is experienced as self-evidently performative: we might therefore expect that new kinds of identities will be enacted on-line, and that participants will frame these identities as performances rather than judging them in terms of their truth or authenticity. This article uses a long-term ethnographic engagement with one internet social setting - the `sexpics' trade on Internet Relay (...) Chat (IRC) - to argue that neither of these expectations is met there. First, the sexual act and identities performed tend to be conventional in relation to off-line heterosexual norms and (pornographic) representations. Second, authenticity is a fundamental criterion by which participants understand and manage their on-line experiences: they veer between complete cynicism (their inability to authenticate the other meant according the relationship and the other no weight or commitment) and a desire for involvement that depended on pursuing startegies for authenticating the other, for being able to treat the other's performances as real rather than merely realistic. Significantly, these strategies of authentication were attempts to fix the other in a body or body-like presence, one which persists over time and is locatable in space, and which is therefore ethically accountable and trustworthy. (shrink)