The securitisation of 'cyberspace' has seen a raft of new security risks emerge, with governments expanding their national security agenda to counter these cyber-threats against 'the digital homeland'. Despite the benefits of global connectivity, issues of (in)security - from big data collection, to mass-surveillance, to the spread of misinformation - are not far detached from questions around the societal value of computers and computer networks. How we conceptualise security relies on assumptions about security, including deciding whom or what requires securing. Constructing cybersecurity explores the role and impact of expertise within the internet security industry in constructing a dominant cybersecurity knowledge that conflates cybersecurity with national security. Highlighting the assumptions and limitations of contemporary knowledge within the field of cybersecurity, Andrew Whiting argues that these security professionals have formed communities of mutual recognition with the state that serve to entrench the centrality of the latter while strengthening their own position within an extended strategy of neoliberal governance.