In my novel, there is a mention of the Internet. When editing, I stopped to ask, “Is Internet capitalized?” My memory said yes, but my inner three-year-old asked, “Why?”
Grammar Girl of http://grammar.quickanddirtytips.com/capitalizing-proper-nouns.aspx answered the question simply. Internet is a proper noun:
Most language experts including the Associated Press and the editors of the Chicago Manual of Style and the Yahoo Style Guide, believe the Internet is one big specific network that people visit, so they recommend capitalizing the word “Internet.”
On the other hand, the Web is populated by many different websites, so “website” is not capitalized. It is a generic term that can be used to describe many different locations.
“Internet” is a proper noun because it refers to something specific, whereas “website” is a common noun because it can be used to refer to many different places on the Internet.