This Article offers a general framework for applying the Fourth Amendment to the Internet. It assumes that courts will seek a technology-neutral translation of Fourth Amendment principles from physical space to cyberspace, and it considers what new distinctions in the online setting can reflect the function of Fourth Amendment protections designed for the physical world. It reaches two major conclusions. First, the traditional physical distinction between inside and outside should be replaced with the online distinction between content and non-content information. Second, courts should require a search warrant that is particularized to individuals rather than Internet accounts to collect the contents of protected Internet communications. These two principles point the way to a technology-neutral translation of the Fourth Amendment from physical space to cyberspace.