The “Internet” officially should be capitalized. I certainly don’t capitalize it, however. This is just a theory, but I’ll bet that there is a clear difference in who capitalizes and who doesn’t. I’ll bet that those who were born after, say,1985 would just write “the internet” without capitalization.
Why? Well, you don’t capitalize “the sky” or “the ocean” or “the highway system”. For our generation, our entire adult lives and some of our formative years has seen the internet as a pervasive network, almost natural in how it surrounds and manifests in many ways and large enough so that it takes years of study to understand it. It ceases to be a proper noun thing that needs to be identified as such and instead is just a part of the world that we refer to from time to time.
It helps that there is no longer a clear boundary of what is and is not the internet. Is your phone part of the internet? How about when in airplane mode- is it a part of the internet that is just temporarily disconnected? How about your body, bathed in wifi and 4G signals, even though it can’t understand what those signals mean. Does the transmission of these into space count as the end of the internet? Is the internet then continually expanding into space at the speed of light in an ever-expanding sphere?
I’ll bet that our grandparents capitalized the “highway system” at least at first, and that their parents never got out of the habit. When this plane lands I’ll do some research- currently it’s a temporarily disconnected section of the internet, regardless of what Delta might claim on the little light above my seat that says “wifi”.
Now that I am on the ground with actual internet access, it looks like I’m not the first to think of this:
There is even a Wikipedia page on it, which seems to suggest that lowercase is inevitable but right now the ‘official’ spelling is with an uppercase ‘I’: http://en.wikipedia.org/wiki/Capitalization_of_%22Internet%22