Editing History of the Internet (section)

==Growth in demand==
Global Internet traffic continues to grow at a rapid rate, rising 23% from 2020 to 2021<ref>{{Cite news|last=Mauldin|first=Alan|date=September 7, 2021|title=Global Internet Traffic and Capacity Return to Regularly Scheduled Programming|work=TeleGeography}}</ref> when the number of active Internet users reached 4.66 billion people, representing half of the global population. Further demand for data, and the capacity to satisfy this demand, are forecast to increase to 717 terabits per second in 2021.<ref>Cisco 2021 VNI Forecast p2</ref> This capacity stems from the [[Optical amplifier|optical amplification]] and [[Wavelength-division multiplexing|WDM]] systems that are the common basis of virtually every metro, regional, national, international and submarine telecommunications networks.<ref>{{Cite book|last1=Grobe|first1=Klaus|title=Wavelength Division Multiplexing: A Practical Engineering Guide|last2=Eiselt|first2=Michael|publisher=John T Wiley & Sons|year=2013|page=2}}</ref> These [[optical networking]] systems have been installed throughout the 5 billion kilometers of [[fiber optic]] lines deployed around the world.<ref>Corning Glass Products/Optical Fiber</ref> Continued growth in traffic is expected for the foreseeable future from a combination of new users, increased mobile phone adoption, machine-to-machine connections, connected homes, 5G devices and the burgeoning requirement for cloud and Internet services such as [[Amazon (company)|Amazon]], [[Facebook]], [[Apple Music]] and [[YouTube]].