Up till now, i've commonsensically used "the Internet" to denote, essentially, everything that i can access or receive and anyone i connect with when i "go online" (connect my computer to data that is not on my computer's harddrive). In other words, i've used "the Internet" to denote the sum of all that's online.

Incorrect. The sum total of all that is metaphorically referred to as "online" is most properly called Cyberspace. Some people extend cyberspace to include non-computer related technologies and forms of communication not involving technology, but for the most part, common usage of the term Cyberspace has narrowed over the years to be specific to CMC. Cyberspace predates The Internet and is a superset of The Internet. Cyberspace includes proprietary networks and protocols that existed before the Internet was conceived of and still exist outside of it.

I've always assumed commonsensically that "the world wide web" simply denotes the network of computers that are "online" (all or part of the time). Since what's online has to rest (or am i missing some basic tech fact?) on some computer, and since to access what's on a particular computer, that computer needs to connected to other computers, "the World Wide Web" and "the Internet" as i understood their meaning refer to the same referent.

Incorrect. The Internet proper is a distributed network of networks which consists of a common set of technical protocols that serve as the foundation upon which almost all CMC services or groups of services currently rest, including the WWW. The Internet is essentially an open communications platform and agreement upon which services are built. The Internet itself doesn't do anything. What makes The Internet special is what it allows you to build with it. The WWW is a subset and extension of the The Internet, consisting of both a communications protocol (HTTP) and a page markup language (HTML), whose specific purpose is the presentation of information in a format that previously was only possible via desktop publishing. In other words, the WWW was created in order to move some aspects of DTP from your local hard disk onto the larger network. Previously, most information on the net was served in extremely simple ASCII text formats. The Internet predates the WWW. The WWW is a recent extension and addition to The Internet. Before the WWW, there were other cruder protocols and services which had a similar function and purpose. They went by names such as ARCHIE, VERONICA, GOPHER, and WAIS.

also, up till now i also thought of "cyberworld" as an a term interchangeable with the other two terms, but that leaves me with no term to denote the "life-world" of people online, as distinguished from "the Internet" as defined above. Could "cyberworld" be used to denote this "life-world", or will that be another gross carelessness with definitions (i can almost feel Thomas Hobbes standing behind me getting ready to slap me ... )

Cyberspace is definitely NOT interchangeable with The Internet or the WWW. As I said before: Cyberspace is a superset of The Internet. Cyberspace predates The Internet. Cyberspace exists outside of The Internet. The Internet is a superset of The WWW. The Internet predates The WWW. The WWW is a subset and extension of The Internet. Art