And like the technologies themselves, digital jargon changes and expands all the time. Just when you thought you’d mastered stuff like RAM (computer memory) and GSM (the cellphone technology invented in Europe), new terms pop up like weeds on your lawn.

So here’s a quick and dirty glossary designed to make holiday shopping for the latest tech products feel less like taking the SATs.

Computers

Some of the newest terminology to know when you’re shopping for a computer, whether it be a Windows PC or an Apple Macintosh, involves the processor, the chip that’s the brain of the box. Until recently, most consumer computers had a single processor. Now it’s common to find them with so-called dual cores, which in effect means two processors packaged into one chip. Two cores won’t make your word processing or email go any faster, but they do potentially give you more horsepower for such heavy-duty tasks as gaming or video editing. I say “potentially,” because to make the most of a dual-core processor, you need software that sends some work to each core, and most programs are not yet designed to do that.

The labeling of these new processors is also confusing. Intel called its first consumer laptop dual-core chip the “Core Duo”; now there’s a second generation known as the “Core 2 Duo.” (In techland, apparently, the “2 Duo” moniker is assumed to be crystal clear.) And there are still some single-core Intel processors, dubbed “Core Solo.”

For laptops in general, one of the latest terms you’ll encounter is “ExpressCard,” which refers to the new version of that slot on the side of the machine into which you can pop a wireless receiver or some other add-on. For years these slots have adhered to a standard called “PC Card,” but the latest laptops are showing up with slots that follow the new ExpressCard standard. Worse yet for confused consumers, it comes in two flavors: a narrower one called ExpressCard/34, and a wider one called ExpressCard/54. And naturally, neither can accept cards designed for the older, PC Card standard.

Cellphones

One hardly knows where to begin when talking about cellphone jargon. But an obvious source of confusion is the baffling nomenclature being given to the various new high-speed cellphone networks that can transmit a wide assortment of material — music, video clips and web sites — to phones at speeds rivaling home broadband.

If you’re shopping for a phone at Verizon or Sprint, the high-speed capability is called “EVDO” or “EV-DO” (which stands for Evolution Data Only or Evolution Data Optimized). At Cingular, it’s known as “HSDPA” (for High-Speed Downlink Packet Access).

Since T-Mobile doesn’t have a network in this speed class, salespeople there will brag instead about “EDGE” (Enhanced Data Rates for Global Evolution), which, despite its aspirational name, is a much slower technology.

TV

Buying a television used to be simple. No more. There’s a whole new vocabulary for digital TV shopping. It’s too expansive to cover completely in this space, but here are a few select terms.

In addition to the familiar plasma and LCD (liquid crystal display) sets, which have an expensive digital panel at the front, there’s now a third type of screen, called a “microdisplay.” This is actually a rear-projection television, although much skinnier than the old behemoths. There are three main microdisplay types. Each uses a different sort of very small digital circuit in the rear of the set to generate the picture, which is then projected onto the large screen at the front. And naturally, each has its own jargony name. The first, called “DLP” (digital light processing), uses a special chip loaded with minuscule mirrors. The second, confusingly called “LCD,” uses a tiny LCD chip. The third, “LCoS” (liquid crystal on silicon), is sort of a hybrid of the other two, in that it uses both liquid crystals and mirrors.

And don’t forget the digital video recorder — the now almost mandatory add-on used to record and save programs on hard disks inside cable and satellite receivers or inside a stand-alone unit — which unfortunately goes by two names. Sometimes it’s called a “DVR” (digital video recorder) and sometimes a “PVR” (personal video recorder), but really, they’re the same thing. You might even hear the technology referred to as “TiVo,” which is actually the best-known brand of digital video recorder. Think of TiVo as the Kleenex of DVRs — its name is sometimes used as a generic term for the whole category.

Wireless

Wi-Fi wireless networks are now pretty familiar. Many people even know they come in two main speeds, designated by letters. The “b” variety, which was the first version to gain public acceptance, was succeeded by the “g” variety, which is faster and backwards-compatible with “b.”

Nice and simple, right? Not for long. Chaos has come to the Wi-Fi world in the form of a new standard,”n,” which is supposedly even faster than “g” and, more important, offers longer range. The problem is, the engineering committee that sets such standards has been taking forever to certify “n,” so companies have begun selling Wi-Fi gear that purports to use the “n” standard in some form but may not be compatible with it when it finally emerges. Last year there were “pre-n” products, which used some parts of the emerging standard; this year there are “draft-n” products, based on a draft of the proposed “n” standard. Stay tuned for the real thing.

But the most important Wi-Fi term of the moment is “MIMO,” short for multiple-input multiple-output. This is a technique that can greatly improve range and speed by capturing formerly stray parts of a wireless signal and merging them. It is expected to be a key component of the “n” standard, but is already in some “g” products, as well as in the “pre-n” and “draft-n” products.

Broadband

There are two main types of high-speed Internet service: DSL (digital subscriber line) is sold by phone companies, while cable modem service is sold by cable companies. Most people know these terms.

But now there’s a third type, called “fiber optic,” being sold in some parts of the country. This technology uses glass fibers, lit up by a laser and connected directly to your home. (Some other systems use fiber under the street, but not running right up to the house.) The best-known brand of fiber-to-the-home broadband service is Verizon’s “FiOS,” which can deliver TV channels as well as the Internet.

All broadband service providers boast about their speed, and they tend to do so in techie jargon. Slower broadband is measured in kilobits per second, abbreviated as “kbps.” Faster speeds are clocked as megabits per second, or “mbps.” (Note that these terms end in bit, not byte. The latter ending is normally used as a measure of storage capacity, not speed.) One megabit equals 1,000 kilobits. So a DSL line that tops out at 768 kilobits per second, for example, isn’t nearly as fast as one that registers three megabits per second.

Music

Almost everybody knows that MP3 (MPEG-1 Audio Layer 3) is the most common format for digital music files. But what is AAC? And how about WMA?

All of the above are compressed formats, meaning they take a song that would occupy lots of space on a disk and squeeze it down to a fraction of its original size while trying to preserve the sound. AAC (Advanced Audio Coding) is an industry-standard music-compression format favored by Apple, while WMA (Windows Media Audio) is a proprietary music-compression format that is owned and used by Microsoft. Which of the three you prefer depends on your taste.

Both AAC and WMA are available in two versions. One is an “open” version, which gets created when consumers convert their CDs into these digital formats, and imposes no restrictions on usage. The second is an encrypted, or copy-protected, version, which includes code that restricts how often and under what circumstances the song can be played or copied. Songs sold at Apple’s iTunes Music Store are in the encrypted version of AAC, while songs sold by music services that use Microsoft software are sold in the encrypted version of WMA, meaning there are limits to what you can do with these files.

And the cellular broadband services, such as Verizon Wireless’s BroadbandAccess, can operate at speeds roughly equivalent to, and sometimes well beyond, the speed of basic wired home DSL service. That means you can surf the Web, and get email and large attachments pretty efficiently.

The card for the Verizon network

A small percentage of users hook up to these cellular broadband networks using laptops that have the necessary gear built in. Another small group uses a cellphone as a modem. But most users of these networks use external cellular-modem cards that plug into a standard slot on the side of their laptops. Therein lies a problem.

The computer industry is in the process of dumping that standard slot, called a PC Card slot, for a new, incompatible slot called ExpressCard. So, buyers of many new laptops are finding their cellphone modems are obsolete.

Now, Novatel, a leading maker of these cards, has come out with a couple of new ExpressCard versions for cellular broadband networks. One, which works on Verizon Wireless’s network, is already on the market, sold by Verizon and by Dell. The second, which works on Cingular’s BroadbandConnect high-speed network, will go on sale from Dell and possibly Cingular later this year, likely late November.

I have been testing the Verizon version of the card, called the V640, as well as a pre-release model of the version that works with Cingular, which Novatel calls the Merlin XU870. The tests not only gave me a chance to evaluate the cards themselves, but also to compare the Verizon and Cingular high-speed networks.

My verdict: The cards were easy to set up and use, and worked well. But the two high-speed networks are very different. While Cingular gave me higher speeds than Verizon in a couple of locations, the Verizon Wireless BroadbandAccess network crushed Cingular’s BroadbandConnect in most places I compared them.

This wasn’t a rigorous scientific test. I used two different laptops, an Apple MacBook Pro and a Dell Latitude D820. The Cingular tests were all conducted on the Dell, because the Mac software for the Cingular card won’t be ready until the card goes on sale. The Verizon tests were all conducted on the Mac. On both machines, I used the test service at speakeasy.net, accessed via the Firefox Web browser.

Also, I tested the cards in only Washington and New York City, and on Amtrak’s Acela Express trains in between. That is a heavily populated region; it’s also Verizon’s home territory, and Cingular might have done better in other parts of the country. Verizon has been rolling out its high-speed network since 2003; Cingular is well behind. Verizon offers the service in 185 metro areas; Cingular is in just 75.

Both cellphone carriers charge $60 a month for unlimited data service using the cards, if you have a voice plan with them. The new Verizon card costs $180. The new Cingular-compatible card is likely to cost $50 more.

The cards look nearly identical, and each works on both Windows and Macintosh computers. On Windows, you must connect using special software. On the Mac, you can simply use integrated software from Apple, if you choose. Both cards have small flip-up antennas and indicator lights. Both worked fine.

Verizon’s high-speed service is often called EVDO, for its underlying technology. Cingular’s service uses a technology called HSDPA.

In my tests, which involved about 20 head-to-head comparisons, the Verizon card and network averaged 818 kilobits per second “downstream” (to get Web pages, and to receive email and attachments) and 113 kbps “upstream” (to send email and files).

By contrast, the Cingular-compatible card averaged just 463 kbps downstream and 77 kbps upstream. Plus, during the three-hour train trip, Cingular disconnected me, or simply had no coverage at all, eight times. Verizon did so only once. Verizon has a deal with Amtrak that supplies data service inside the trains, which helped, but this in-train signal doesn’t include the high-speed EVDO service.

Cingular did beat Verizon in two places: my hotel in New York’s financial district and my office in downtown Washington. In the hotel, the Cingular service got a downstream speed of 1753 kbps — its highest in my tests — versus 888 kbps for Verizon and just 747 kbps for the hotel’s expensive wired Internet service. In my office, Cingular got 1133 kbps downstream versus 644 kbps for Verizon.

But the downstream speeds varied wildly. In Trenton, N.J., the Cingular service managed just 16 kbps. The best for Verizon was 1366 kbps in New York’s Penn Station, while its worst was 132 kbps between big cities in New Jersey.

I recommend both new cards. But unless you live, work and travel in very strong Cingular coverage areas, Verizon is the better choice for high-speed wireless data, at least today.

Email me at mossberg@wsj.com.