This thesis examines site-specific art on the Internet from the popularisation of the World Wide Web in 1994 until 2001. The artists studied here are those primarily associated with the term 'net.art', although other artists not associated with this term have also been considered wherever relevant. The generic term I use to designate all these artists is thus 'net art'. The central aim of this thesis is to understand how Internet technology has been used by artists to extend certain avant-garde tendencies in the context of a globalised and networked society. Setting artwork in the busy multi-media 'information superhighway' also used for economic and commercial transactions, media production, private communication, cultural projects, political debate and organisation, creates new proximities and relationships between art and other forms of communication and action. Indeed it can be said of the Net in general that it produces a whole series of new proximities and relationships, including those between geographically disparate communities, the space of the public and private and between the corporate and cultural spheres. It is the assertion of this thesis that the mutability and transferability of digital information is instrumental to this new organisation of social and cultural life. Through a series of thematic discussions, I explain how the participation of art within this informatic regime works both to reveal its inherent qualities and, conversely, to interrogate the ontology of art. Taking Walter Benjamin's concept of the recession of the artwork's aura in the age of mechanical reproducibility as a starting point, I examine how informatic reproducibility both fulfils and confounds his thesis. I conclude that although the use of information technology works to extend the avant-garde project by blurring boundaries between art and 'life praxis', art is nonetheless able to retain its ontological distinctness – its aura. With regard to net art I locate the preservation of its aura within the unpredictable mutations and instability of digital information.