This report presents a framework for analysing Internet openness, the factors that influence it, and its effects. It also presents initial qualitative and quantitative evidence on the effects of Internet openness. Among the key findings are that Internet openness consists of many technical, economic and social elements and that overall openness is vital for reaping the Internet’s potential benefits. Those benefits include positive effects on trade, innovation and entrepreneurship, macroeconomic performance, and social wellbeing. However, openness also presents challenges, as bad actors sometimes take advantage of it when conducting malicious activities. While the global, decentralised and interconnected nature of the Internet prevents individual countries from determining openness unilaterally, governments nevertheless take policy actions that can affect openness. Policymakers should bear in mind that even though there are legitimate reasons for setting certain boundaries, drifting away from a general preference for Internet openness is economically and socially costly.