other restrictions for citizens of or recent travellers to the most affected areas. Other countries and regions have imposed global restrictions that apply to all foreign countries and territories, or prevent their own citizens from travelling overseas. The imposition of border controls has curtailed the spread of the virus, but because they were first implemented after community spread was established in multiple countries in different regions of the world, they produced only a modest reduction in the total number of people infected These strict border controls economic harm to the tourism industry through lost income and social harm to people who were unable to travel for family matters or other reasons. When the travel bans are lifted, many people are expected to resume traveling. However, some travel, especially business travel, may be decreased long-term as lower cost alternatives, such as teleconferencing and virtual events, are preferred. A possible long-term impact has been a decline of business travel and international conferencing, and the rise of their virtual, online equivalents. Concerns have been raised over the effectiveness of travel restrictions to contain the spread of COVID-19. Aspects Contemporary border control policies are complex and address a variety of distinct phenomena depending on the circumstances and political priorities of the state(s) implementing them. Consequently, there are several aspects of border control which vary in nature and importance from region to region. Air and maritime borders In addition to land borders, countries also apply border control measures to airspace and waters under their jurisdiction. Such measures control access to air and maritime territory as well as extractible resources (e.g. fish, minerals, fossil fuels). Under the United Nations Convention on the Law of the Sea (UNCLOS), states exercise varying degrees of control over different categories of territorial waters: Internal waters: Waters landward of the baseline, over which the state has complete sovereignty: not even innocent passage is allowed without explicit permission from said state. Lakes and rivers are considered internal waters. Territorial sea: A state's territorial sea is a belt of coastal waters extending at most 22 kilometres from the baseline of a coastal state. If this would overlap with another state's territorial sea, the border is taken as the median point between the states' baselines, unless the states in question agree otherwise. A state can also choose to claim a smaller territorial sea. The territorial sea is regarded as the sovereign territory of the