Not long ago, when desktops and laptops were the main computers we used every day, PC makers peddled what’s known as the megahertz myth. Manufacturers wanted you to believe a machine’s “clock speed” was the key measure of its responsiveness. This isn’t true—a processor’s design is just as important as its clock. We all fell for it just the same, just as we’ve fallen for the megapixel myth, the mistaken belief that a camera that captures more megapixels produces better digital photos.

Thankfully, the tech industry has been gradually dropping its murky jargon. You can credit Apple for the trend. Beginning with the iPod and continuing with the iPhone and iPad, Apple made a deliberate effort to avoid mentioning tech stats in its marketing. When CEO Tim Cook unveiled the new iPad last week, he didn’t tell you its clock speed nor mention how much RAM it has. He just told you it’s better than the old iPad. Even when Apple does mention specs, it tries to do so in a way that most humans can understand. The first iPod was said to give you “1,000 songs in your pocket,” not 5 gigabytes of space for your MP3s.

Apple hasn’t purged every tech spec, though—the new iPad still touts the megapixel capability of its camera, for instance. And even worse, the iPad now carries the most consumer-unfriendly spec in all of tech: “4G.” That label, which theoretically specifies a device’s wireless data speed, doesn’t really tell you anything about how fast your gadget might surf the Web. If you see any phone, tablet, toaster, or fridge that’s capable of “4G” networking, you should assume the guy who’s selling it to you thinks you’re a fool. And if you do put any stock in the label, you are a fool. 4G—and, relatedly, “3G”—means nothing. It never has, it never will, and it’s time we banished it from our devices for good.

The emptiness of 4G was highlighted last week, when people who installed the latest iPhone 4S operating system upgrade noticed something that seemed too good to be true: The network indicator on their phones began displaying “4G” rather than “3G.” This change occurred only for people who use AT&T’s cellular service; Verizon iPhone users who installed the upgrade still saw the 3G indicator. Some people took the change to mean that their phones had gotten faster wireless Internet access, but that wasn’t true—the OS upgrade did nothing to change how your phone communicates with cell towers. All that changed was AT&T’s marketing. Early last year, essentially overnight, AT&T began rebranding its 3G network as a 4G network. So now that tired old 3G phone is fresh again—lucky you, you’ve got 4G!

The worst part is that AT&T isn’t completely wrong. According to the narrow, somewhat arbitrary networking distinctions set by the world’s standards bodies, the company can make a plausible argument that its old 3G network is in fact a rival to 4G. To understand why, we need to take an unavoidably technical jaunt through the wonderful world of wireless networking.

Here goes: AT&T’s version of the iPhone 4S connects to the Internet using a wireless standard known as HSPA+. This standard has long been considered a 3G technology, because it is an improvement to the “third generation” of wireless networks. Meanwhile, 4G was a term reserved for new networks that rely on a faster standard known as LTE. The trouble is, engineers have figured out theoretical ways to boost HSPA+ networks to speeds that could beat those of LTE. At some point in the future, HSPA+ networks could achieve blindingly fast speeds of up to 168 megabits per second. LTE networks, meanwhile, will tap out at 150 megabits per second. This possibility makes a hash out of the 3G and 4G labels. If a 3G tech like HSPA+ could outpace 4G LTE, is it fair to tar the promising HSPA+ with the lower G?

Well, yes, it is—because even if HSPA+ networks may beat LTE someday, they don’t today. If you’ve got an HSPA+ device (like the iPhone 4S), you’re likely to achieve download speeds of between 1 and 3 megabits per second. That’s about half the speed of the average U.S. home broadband connection. An LTE device (like the new iPad), meanwhile, will let you download at speeds of 5 to 12 megabits per second, according to both AT&T and Verizon. That’s about on par with your home broadband line. In practice, then, real 4G handily beats faux 4G.

For wireless carriers, though, real 4G networks—that is, LTE networks—are expensive and time consuming to install. In 2010, T-Mobile decided that it would focus on improving its 3G network rather than build out its LTE capabilities. The company began touting that its new HSPA+ network could offer “4G speeds.” This marketing trickery was criticized by everyone in the industry, including AT&T. “I think that companies need to be careful that they’re not misleading customers by labeling HSPA+ as a 4G technology. We aren’t labeling those technologies as 4G,” an AT&T spokesman said back then.

But now AT&T has changed its mind. Mark Siegel, a spokesman, told me that the company’s about-face came as a result of a 2010 decision by the International Telecommunications Union that HSPA+ could be referred to as a “4G.” This change is very convenient for AT&T, because while its LTE network is smaller than Verizon’s, its HSPA+ network is the largest in the country. If 4G is taken to mean LTE, then AT&T loses to Verizon in the coverage wars. But if both HSPA+ and LTE are 4G, then AT&T’s network looks really great, and its claim that it’s the largest 4G carrier in the country isn’t total balderdash.

Not surprisingly, that’s exactly the line Siegel pushed with me. “If you have one of our LTE devices—let’s say it’s the new iPad—and if you leave an area that is covered by LTE, then, with us, you’ll go back to HSPA+ technology, which offers such fast speeds that you might not notice the difference,” he says. (Even though AT&T calls both its LTE and HSPA+ networks “4G,” it displays the 4G label only when you’re using HSPA+. When you’re in LTE territory, it says “LTE.”) On the other hand, Siegel says, if you’re using an iPad built for Verizon’s network, you’ll fall back to Verizon’s old 3G network—which runs on a technology called EV-DO—when you leave an area covered by LTE. EV-DO is recognized as being substantially slower than HSPA+. “You will experience a jarring drop in speed,” Siegel says. “It will be a noticeable difference, and that shows the advantage of our two 4G networks.”

I ran this argument by a spokeswoman for Verizon, and she didn’t dispute what Siegel says. Verizon’s 3G network is in fact slower than AT&T’s 3G-masquerading-as-4G HSPA+ network. If you’re looking for the fastest speeds when you’re not connected to an LTE network, you should go with AT&T.

But even that argument obscures the bigger problem with the “4G” term. The truth is, the speeds that you’ll get on a given device on a given network are determined by a variety of factors other than the protocol your network uses. This morning I asked my followers on Twitter and Facebook to run a speed-test app on their iPhones and report their cellular data speeds back to me. The most obvious trend was that there was no trend: People got a wide variety of downloading speeds, ranging from 0.18 megabits per second all the way to more than 3 megabits per second. Sometimes Verizon iPhones were faster than AT&T ones, even though AT&T’s protocol is faster. Sometimes the iPhone 4—which has a slower networking modem than the 4S—was faster than its successor. Most importantly, most reported speeds were far slower than advertised speeds.

This suggests that mobile devices, no matter what spec that cell carriers attach to them, should come with a warning label: “BEWARE: What you’re promised will never be what you get.”