Digital Cameras

Megapixels: This term describes the highest resolution photo a camera can take. Often mistaken as the most important factor in a digital camera, a high megapixel count — such as 10MP or more — isn’t necessary for the average user unless he or she plans on heavily editing or enlarging photos. Most new digicams offer between five and eight megapixels, which is usually more than enough.

Optical or Digital Zoom: Optical zoom, determined by the physical movement of a lens, matters much more than digital zoom, which digitally alters an image using the camera’s internal computer. Camera companies still try to confuse potential buyers by listing a camera’s total zoom, or the optical and digital zooms multiplied together. Ignore total zoom numbers and instead focus on optical, which now averages around 5x for many new cameras.

Image Stabilization: When generously sized LCD viewing screens started replacing optical viewfinders, they also forced users to hold their cameras at arm’s length, making for plenty of blurry photographs. To remedy this, camera manufacturers have added image stabilization, tools once found only in high-end SLR models. Optical (also called “mechanical”) and digital image stabilization correct for unsteady hands and moving subjects, respectively. Cameras with both types advertise dual image stabilization, which corrects for both situations and costs more.

Mobile Devices

HSDPA and EVDO: HSDPA, or High Speed Downlink Packet Access, is the name for AT&T‘s 3G, or third generation, mobile network that operates at roughly the speed of a slower DSL in a home. HSDPA is available in most major metropolitan areas and is seen as the competitor to Verizon and Sprint’s EVDO (Evolution Data Only) networks, though the popular iPhone runs on AT&T’s network using Wi-Fi and EDGE technology rather than HSDPA.

Multi-Touch Technology: Most popularly found on Apple’s iPhone and iPod touch, multi-touch is starting to show up in other products, such as in Microsoft‘s Surface, a coffee-table-like computer. Rather than just responding to on-screen touches, this technology enables moving, resizing and zooming pictures and Web pages using one or more fingers simultaneously. Look for many more devices — mobile and otherwise — to incorporate multi-touch in the future.

GPS: Global Positioning Systems are most often found in cars — either built-in or on portable devices from companies like Garmin and TomTom. These gadgets use satellite technology to determine geographic location, and high-end models even display Web content like news and weather along with directions. GPS integration in mobile devices can be used to plot routes in cars, can help users find nearby businesses while on the go and can link friends by showing one where the other is located and what they’re doing.

Digital Music

DRM: Digital rights management is a set of standards that protect the intellectual property rights of online content like music and videos, preventing it from being illegally distributed across the Web. In the past year, Vivendi‘s Universal Music Group, Apple and (most recently) Sony BMG said they will start selling DRM-free versions of songs, often for a higher price. In Apple’s iTunes store, these files are called “iTunes Plus” and aren’t restricted like other iTunes content.

MP3: MP3 files are open, without any DRM restrictions. Files that you rip (copy) from your own CDs are usually converted into MP3s, though iTunes users can automatically rip tracks into that program’s special format, called AAC. MP3 files can be uploaded to social-networking sites for sharing with friends and online communities.

These file types are protected by rights that tie them to specific players. Generally, AAC files make up the majority of tracks sold on Apple’s iTunes store and play only on Apple’s iPods; WMA files are Microsoft’s version of proprietary files.

Wi-Fi

The popularity of Wireless Fidelity, or Wi-Fi, brings this technology to more and more portable devices like the iPod Touch and Microsoft Zune and gives companies good reason to incorporate Wi-Fi receivers in new computers — laptops and desktops alike. While available in many flavors, different letters like b, g, a and n stand behind Wi-Fi’s more technical name, 802.11, to help discern one version from another according to characteristics like speed and compatibility. The latest version, “n,” offers the greatest range and speed, and “n” devices are usually compatible with earlier versions.

Televisions

HDTV: High-definition television has now become the standard, capable of displaying vastly better pictures, provided the source is also HD. Today’s more popular flat panel HD televisions are LCDs, or liquid crystal displays, though plasmas still hold their own. Recording HD content can’t be done with a regular digital video recorder; instead, a special HD recorder is required to capture this higher quality content.

480p vs. 1080i vs. 720p vs. 1080p: These numbers refer to the resolution, or sharpness, of a digital display, while “p” stands for progressive and “i” stands for interlaced. A resolution of 480p, known as EDTV or Enhanced Definition TV, is found most often in low-end plasmas or LCD screens. A TV with a resolution of 1080p is currently considered the Holy Grail, and costs the most. But 1080p pictures usually can’t be distinguished from less expensive 1080i or 720p pictures by average viewers at the typical distances from which most folks watch TV.

Blu-ray vs. HD DVD: Blu-ray and HD DVD are incompatible high-definition disc formats that continue to fight a seemingly endless battle to replace the DVD. The Blu-ray camp is led by Sony and the HD DVD camp is led by Toshiba. The two formats aren’t so different, technically speaking, but their very existence is confusing to consumers. The recent decision made by Time Warner‘s Warner Bros. to use Blu-ray gives Sony’s side a boost, and now Viacom‘s Paramount is rumored to be switching to Blu-ray from HD DVD. Dual-format players from Samsung and LG offer some solace.

Email: mossbergsolution@wsj.com

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.

Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability. This week my mailbox contained questions about watching Major League Baseball’s streaming Webcasts of games, the capacity of digital music players and the security of Wi-Fi.

I just bought a new Mac and I love it, but I am a die-hard Yankees fan and I find that, with the Mac, I can’t watch Major League Baseball’s streaming Webcasts of games. Is there a way around this?

Since I am a huge Red Sox fan, I hesitate to help you … but I will.

It doesn’t work, because MLB.com this year switched to a Microsoft video format that the Mac version of Windows Media Player can’t handle and it doesn’t support the Safari Web browser that Apple includes on every Mac. There is a workaround: download and use Firefox, instead of Safari; and download and install Flip4Mac, a free program that allows QuickTime to handle the newest Windows Media video format. You can get it at: http://flip4mac.com/.

But even this solution is seriously flawed. The problem — and the Flip4Mac people are working on it — is that it plays only for a few batters or so, and then you have to restart it by relaunching the TV feed in the Web site. This is a pain, but it does work, sort of.

A better solution is to simply run Windows on your Mac, and then play the MLB videos on that. I do this using a product called Parallels desktop, which runs Windows inside a window on your Mac. It’s available at: www.parallels.com.

I am not clear about capacity on digital music players. As far as I can determine, most music CDs run to about 600-700 MB, so a mere 10 CDs would fill most of a 10-gigabyte iPod, correct? On the other hand, I recently read that all of Mozart’s works would fit on a 10-GB iPod. So what’s wrong with my calculations?

When companies calculate the capacity of digital music players in terms of songs or CDs, they base their calculations on the use of music files that have been drastically shrunk from their original size on a CD. This is done by converting the songs to compressed file formats, including the MP3, WMA, or AAC formats. This is what happens when you import, or “rip,” a CD into iTunes or Windows Media Player on your computer in preparation for loading the songs onto a portable player.

A typical MP3 file compresses CD music by a factor of 10 or more. So, a 650-megabyte CD might take up just 60-65 megabytes on a computer or a portable player. There is a price to this compression: The quality of the music file is degraded. However, most people find the quality acceptable, especially with common types of music — pop, rock, country and hip-hop.

Many audiophiles and classical-music fans choose to compress their CDs less drastically, seeking a balance between space-saving and quality. This can be achieved by changing the settings in your music software. Others opt for no compression at all, though, as you noted, that severely limits how much music you can squeeze onto a portable player.

I would like to link up the computers in my home wirelessly but am apprehensive about the security aspects. Is it safe to use Wi-Fi?

Yes, in almost all cases. Wi-Fi networks come with an optional security feature that requires anyone using them to know your password. So, you can turn that on. Even if you don’t, your files would be at risk only if you had a neighbor close enough to access the network who is both skilled enough and nasty enough to want to poke around in your files. In most neighborhoods, that combination is pretty rare, as is the likelihood that hackers will drive down your street in a van with a laptop and steal your secrets.

However, I would also maintain a software firewall and turn off all file-sharing features of your operating system and other software.

There are exceptions. If you live in a large apartment building, the number of potential snoopers who are strangers goes way up, since many more people will be close enough to access your network than they would be in a suburban neighborhood of single-family homes. Also, no security system is perfect. Determined hackers could theoretically break into any wireless network.

But, in most scenarios, I believe Wi-Fi is safe.

* * *

Because of the volume of e-mail I receive, I can’t routinely answer individual questions by e-mail, or consult on individual problems or purchasing decisions. I read all questions I receive and select three each week to answer in the column.

• Write to Walter S. Mossberg at mossberg@wsj.com