Located below are a few links I find give more information learn in these two chapters.
http://www.pcmag.com/slideshow/story/286035/30-years-of-consumer-storage-from-floppy-disks-to-ssds
http://www.computerhistory.org/revolution/personal-computers/17
http://physiotalk.co.uk/2014/02/09/quick-guide-to-different-types-of-social-media/
dme110 