A global city, also called a power city, world city, alpha city or world center, is a city which is a primary node in the global economic network. The concept comes from geography and urban studies, and the idea that globalization is created, facilitated, and enacted in strategic geographic locales according to a hierarchy of importance to the operation of the global system of finance and trade. The most complex node is the "global city", with links binding it to other cities having a direct and tangible effect on global socio-economic affairs. The term "megacity" entered common use in the late 19th or early 20th centuries; one of the earliest documented uses of the term was by the University of Texas in 1904. The term "global city", rather than "megacity", was popularized by sociologist Saskia Sassen in her 1991 work, The Global City: New York, London, Tokyo. "World city", meaning a city heavily involved in global trade, appeared in the May 1886 description of Liverpool, by The Illustrated London News. Patrick Geddes later used the term "world city" in 1915. More recently, the term has focused on a city's financial power and high technology infrastructure, with other factors becoming less relevant.