No, you're on "the internet." "Internet" is a generic term, and it refers to a network where they speak IP (Internet Protocol). The internet is short for "the world-wide internet." As a side note, you might be reading this on USENET, but not on "the USENET." USENET is a proper name (drawn from users' network) inspired by the way USENIX was named for "users of Unix."

Note: Since "the internet" is becoming a proper name, the Internet is also a valid form.

I am on the internet

Perhaps you are, but there have come to be many meanings for this term and it's better to use another term that really describes your state. For most "on the internet" this phrase means to have a dedicated TCP/IP hookup, where you can run programs like "telnet", "ftp" and WWW clients like "Mosaic." It might be best to call this a "live internet connection." A common mistake is to confuse being able to send E-mail over the internet through a gateway machine with being "on the internet." Call this being on the e-mail net. There are further divisions:

56kb or higher dedicated connection: For the purist, this is really being on the internet. You can run servers.
Dedicated modem-speed SLIP/PPP connection: You can run servers but they can only get light use. More for users
Dial-up SLIP/PPP connection: Intermittent connection. Not suitable for having "an internet site" but useful for browsing.
Account on one of the above: Access to the internet, but you're not on it.
Account on machine that talks to one of the above: Usually E-mail only, not really "on the internet."

I read it in an internet newsgroup

The most common misconception: confusion of USENET and the internet. The internet is a communications backbone. Many applications have been written that can use that backbone to send data. USENET is one of them. It's not the same as the internet, it's an application that runs on it, sort of like software and hardware. USENET is a conferencing system, which lets people hold discussions and publish information in a distributed fashion. It's similar to (and both father and child of) the concept of the computer bulletin board, but distributed over tens of thousands of machines.

USENET is a cooperative of machine owners, and a community. And while it often uses the internet to send data, it also works on top of other networks, including modem based telephone transfers. In fact, that's how it got started.

A lot have been written about what USENET is, and this is not the place for it. What's important to understand is that it is something different, that it still has a large existence outside the internet, and you should learn more about that.

However, to confuse you more, I'll say that USENET is a very important part of the internet. It is by far the most important form of conferencing and community on the internet. While mailing lists and chatting software also run over the internet, USENET is the internet's prime community and place to talk, which is why you were talking about an internet newsgroup. USENET both predates and postdates the internet. USENET started its existence using phone lines in 1980. The internet started being called by that name that a few years later, but it's also the direct descendent of the ARPANET, which dates from 1969.

If it's on the internet, it's free to everybody

Actually, no. The internet is (with some special rare exceptions) a point to point network, just like the telephone system. It consists almost entirely of "data phone calls" from one program on one computer to another unique program on another computer. What makes information publishing possible are the applications that use this capability.

One such application is FTP, which allows file transfers from archives. A special form of this, "anonymous FTP" accepts calls from all comers. So a file up for anonymous FTP is freely available to anybody, but this is just one thing you can do on the internet.

USENET newsgroups are also usually generally available, but some are proprietary.

It turns out that some of the most interesting applications of the internet have been the ones that give information to everybody, thus the sentiment above, but this is only because people want it this way, not because it has to be.

Transmitting information over the internet or USENET also does not abrogate its copyright status, any more than leaving 10,000 free copies in the town square or broadcasting to the entire planet do.

Commerce is not allowed on the internet

The world-wide internet is a collection of many, many networks. Some of them have rules regarding commerce. Some do not. The number that do is actually dwindling. If your connections cross a network with rules, they will expect you to follow them. Right now rules primarily apply to a few regional networks and the NSFNet backbone -- but the NSFNet backbone happens to run on top of the ANSNet backbone, and people who sign a deal with ANS (as many regional networks have) can send traffic over those pipes without worrying about such rules.

If you connect to a provider without such rules, you can pretty freely conduct commerce on your own machine, and in traffic to the machines that connect to you for commerce.

But watch out -- some net resources involve using other people's machines. USENET works this way. Those other machines may introduce rules. In addition, many of the networks that don't forbid commerce do have rules about annoying people, whether it's for commerce or not. But some forms of commerce inherently annoy people (such as junk E-mail) and you need to watch out.

Commerce is not allowed on USENET

USENET is a cooperative of tens of thousands of machines. It actually has no rules, so nothing legal is "not allowed." However, it is also a community, and it has social mores, guidelines and history, and certain types of commerce are not welcome in many areas of USENET. One must become a member of the community -- by participating -- not merely a user of it, to find out how each area works.

USENET technology has been used for commerce for some time, actually. For example an electronic newspaper called ClariNet is published in USENET format, and is only available to paying subscribers. (The author of this document is the publisher.)

The Web (Mosaic) is the internet

The World-Wide-Web is a very interesting application of the internet. Mosaic is a program that can talk to WWW servers, don't confuse the Web with Mosaic. As one of the first point-and-click programs, Mosaic attracted lots of attention, but sometimes people think that the Web is the whole internet. There's a lot more -- go and explore.

The internet is a public place

Probably not. Every part of USENET and the internet is privately owned and operated. Some of the sites are themselves public institutions, but in almost all cases they join the net in their private capacity -- ie. their net connection is only for their staff or students, not the public. Freedom of the press belongs to those who own a press, and that means that net site owners hold all the power in their own local fiefdoms. However, the great wonder of the net is that it's relatively cheap to own your own "press" and get on yourself.

The internet is a cesspool of porn and child abuse

There is almost everything on the internet. And it's almost axiomatic that new communications technologies are used for sexual purposes. (Look at what brought 900 numbers and VCRs to public success.) So there is a fair quantity of porn on the net. As the world's most unrestricted medium, you must expect that people will use it in ... unrestricted ways. It is, however, a mistake to think this is the dominant use of the net, it's actually less than 1% of the number of messages that transit the net.

As for child abuse -- well, that gets everybody's attention as a serious crime, but as far as anybody knows there have been only a handful of reported child abusers among the many millions of net users. Chances are this sort of person is much less common on the net than in ordinary society.

You need to know that hard-to-use Unix OS before using the internet

While I've never entirely understood how Unix got its particular hard-to-use reputation in contrast to the harder-to-use pre-Windows MS-DOS, it is true that Unix is the most important OS for internet software. It is usually written first for Unix. However, there is lots of internet software now for DOS, Windows, the Mac and almost every other operating system. Indeed, systems like Windows NT, Novel Netware and Windows 4.0 are now or shortly will be shipping standard with TCP/IP. Of course the quality of the applications and their ease of use depends on the individual programs.

If you want to run an internet server, Unix is still the prime choice, but that's because a multi-tasking multi-user networked OS is generally a requirement for such things.

The internet is nothing but anti-commercial college students and nerds who rudely drive away those who don't follow their philosophy.

There certainly are such people on the net. But there are all kinds of people on the net now, and no one group runs it. Just because somebody speaks authoritatively doesn't mean they are right -- even me. But yes, there is some rudeness to be found on the net, particularly as more people join it who don't know what it is, upsetting some of the balances in the largest functioning anarchy ever built. But thicken your skin and jump in, because you can set the new standards if you are creative enough.

The internet is the biggest network, and it has more of almost every type of person than anywhere else. Squeaky wheels dominate, but they are not the entire picture.