Jurisdiction refers to the legal authority of a state to prescribe, adjudicate and enforce laws. In cyberspace, the determination of jurisdiction becomes complex because cyber activities transcend territorial boundaries, involve multiple actors located in different states, and occur in a virtual environment without clear physical location. Traditional theories of jurisdiction developed under public international law are therefore reinterpreted and adapted to regulate cyberspace. Various theories of jurisdiction are applied to address issues such as cybercrime, data protection, e-commerce, and online speech. The territorial theory of jurisdiction is the most traditional and widely accepted basis. It is founded on the principle that a state has jurisdiction over acts committed within its territorial boundaries. In cyberspace, this theory is adapted through the concepts of subjective and objective territoriality. Subjective territoriality applies when the cyber act is initiated within a state, such as when a hacker operates from a computer located in a particular country. Objective territoriality applies when the effects of a cyber act are felt within the territory of a state, even if the act originated elsewhere, for example, online fraud targeting victims in another country. Courts have increasingly relied on the effects doctrine to assert jurisdiction over foreign-based online activities that cause substantial harm within their territory. The nationality or personal jurisdiction theory is based on the nationality of the offender