Why is this word supposed to be capitalized? Every time I type it in Word or in my email, my spell checker tells me I’m wrong because I never capitalize it. If you look it up in a variety of online dictionaries, you see it both ways, depending on which dictionary it is - but there’s never an explanation why it’s shown one way or the other.

Is "Internet" the name of some kind of "place"? Is it somebody’s copyrighted brand name? I don’t get it.

I refuse to capitalize this word - unless somebody can give me a really, really good reason for doing it. 

Proper nouns (also called proper names) are the names of unique entities. For example, "Janet", "Jupiter" and "Germany" are proper nouns. Proper nouns are capitalized in English and most other languages that use the Latin alphabet, and this is one easy way to recognise them. This fails, however, in German, in which nouns of all types are capitalized. All other nouns are called common nouns. For example, "girl", "planet", and "country" are common nouns. Sometimes the same word can function as both a common noun and a proper noun, where one such entity is special. For example: "There can be many gods, but there is only one God." The Internet has been capitalized "by convention," meaning that has been in the past and probably will be in the future. Various critics disagree as to whether Internet should be capitalized, but the common consensus is to capitalize it rather than not to capitalize it. Webster’s Dictionary says that it should be capitalized, but I think it mainly depends upon its use. When you’re using the word as a proper noun as in the name "the Internet", the global network of networks,then yes, you capitalize it. When you’re using it to refer to any internet, such as a random network of networks, you probably shouldn’t. More explanation: The Internet is the largest internet (with a small "i") in the world. It is a three level hierarchy composed of backbone networks, mid-level networks, and stub networks. These include commercial (.com or .co), university (.ac or .edu) and other research networks (.org, .net) and military (.mil) networks and span many different physical networks around the world with various protocols, chiefly the Internet Protocol.
http://theboard.byu.edu/index.php?area=posts&date=2004.04.24&archives=1

The Internet has been capitalized "by convention," meaning that has been in the past and probably will be in the future. Various critics disagree as to whether Internet should be capitalized, but the common consensus is to capitalize it rather than not to capitalize it. Webster’s Dictionary says that it should be capitalized, but I think it mainly depends upon its use. When you’re using the word as a proper noun as in the name "the Internet", the global network of networks,then yes, you capitalize it. When you’re using it to refer to any internet, such as a random network of networks, you probably shouldn’t.
http://en.wikipedia.org/wiki/Proper_noun

VB

-

The Internet has been capitalized "by convention," [...] The Internet is the largest internet (with a small "i") in the world.

Corresponds to (semi)official Swedish recommendations.

-

More explanation: The Internet is the largest internet (with a small "i") in the world.

If the Internet is an internet, then I suppose the Moon is a moon. But is the Earth an earth? Seems to me there’s only one earth, which must also be the Earth. Makes a lot of sense. I’ll comtemplate that as I sit in my Jacuzzi jacuzzi tonight.

I don’t mean to make light of your explanation. I appreciate it and will begrudgingly start capitalizing Internet and stop clicking "ignore" in my spell check.

It wouldn’t surprise me if the popularity of the lowercase i wins in the long run, though.  With the commonality of chat/messenging services now, and the almost complete absence of uppercase letters in these chats, it is ironic that one of the Internet’s most used features may lead to its transition from formal to informal…

-Tim