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

When it comes to cool hand-held devices, one always stands out in the crowd: the T-Mobile Sidekick. You may have seen photos of Hollywood stars posing with this device like an accessory, or maybe you’ve just seen someone using one and you caught yourself wondering what it was.

The Sidekick, built for T-Mobile by Sharp Electronics Corp., doesn’t look like most common hand-helds, such as the Palm Treo or RIM BlackBerry, which are designed with a screen and keyboard lined up under one another for convenient emailing, phone use and Web browsing. Instead, the Sidekick is meant to be held horizontally and its screen must be twisted out with a dramatic, eye-catching snap in order to use its hidden keyboard underneath. In closed-keyboard position, the device can be held up to your ear vertically to use as a phone.

This week, we tested the latest version of this trendy hand-held, the Sidekick 3. It will officially launch July 10 for $300 with a two-year contract from T-Mobile USA Inc., but is available just for current T-Mobile customers starting today for 12 days.

Testing the Glam Factor

The last edition of the Sidekick — Sidekick 2 — came out almost two years ago, and plenty of improvements have been made in this product category since then, so we were expecting exciting new things from this third edition. We had fun testing the glam factor of the Sidekick 3 this week, using it in clubs, bars and taxicabs with extra screen-twisting snaps just for effect. But while our new gadget earned plenty of approving glances from those in the know, the Sidekick 3 isn’t all it could be.

The Sidekick 3’s most distinctive feature is its flip-out screen, but you can’t dial phone numbers with the screen closed.

Its new design is slightly more tapered than the chunky Sidekick 2, but that’s not saying much. Compared with the 0.45-inch thickness of the recently introduced Motorola Q, the Sidekick 3’s 0.86-inch depth isn’t anything remarkable. The more physically comparable Palm Treo 700p is 0.9 inches deep, but the Sidekick 3’s overall length outstretches the Treo by almost an inch, making it appear larger overall.

The Sidekick 3’s screen is generously sized at 2.62 inches diagonal, due in part to its horizontal layout. But the screen’s resolution is the same as it was on the Sidekick 2: a mushy 240×160 pixels. Compared with screens on other devices that offer greater sharpness and brighter colors, the Sidekick 3’s screen is a definite downer.

While many of the latest smartphones use high-speed EV-DO data networks for zippy Web browsing, the Sidekick 3 only uses EDGE — a much slower technology. When we tried to pull up articles about the World Cup, it took us at least 30 or 40 seconds to load each Web site.

New Trackball

Four navigation buttons that dot each of the screen’s corners make it easy to get around to different areas on this device. We especially liked the Sidekick 3’s trackball, which replaced the Sidekick 2’s up/down wheel so as to enable scrolling in all four directions.

But we were disappointed and a little surprised that the Sidekick’s lousy phone function hasn’t been improved with this version. Because of this device’s flip-out screen, the keyboard and numeric keypad are hidden unless the screen is out. So you can’t dial a number with the screen closed. After opening the screen and dialing, you can flip the screen in again and hold the phone up to your ear, but this back-and-forth process is tiring.

You can call people in your Contacts list with the screen closed by selecting an icon on the screen, because you don’t need access to the keypad for that. But even this process is a bit clumsy compared with the speed-dial functions on standard cellphones.

A few more bells and whistles try to spice up the Sidekick 3. These include Bluetooth, a processor four times as fast as that of the Sidekick 2, and a 1.3-megapixel camera. We found the camera easy to use, and a special button positioned on the top right edge of our Sidekick 3 worked as an easy shortcut to use the camera on quick notice.

We easily emailed photos directly from our photo gallery, using the trackball and navigational buttons to pull up an email format before swinging the screen out to type an email address using the keyboard.

Instant messaging on the Sidekick 3 is well-done, as it was on the Sidekick 2. AOL Instant Messenger, MSN Messenger and Yahoo Messenger come with the device, and we chatted with friends on AIM with ease. The keyboard, though it’s hard to get to, is generously spread out and comfortable to use after typing messages for awhile.

The Sidekick 3 also has a built-in Mini-SD memory-card slot, but we had to call tech support to learn where it was located. This card slot is inconveniently located behind the back panel of the device, meaning you have to actually remove this panel — exposing the battery — in order to use the slot. For users who want to pop their memory cards in and out, this is a real hassle.

Cutesy Extras

If you’re desperate for cutesy extras, the Sidekick 3 is loaded with them. The trackball turns different colors to indicate waiting text messages, instant messages, email or voice mail, and a multitude of sounds chime from the device just for the fun of it. Seventeen cartoon icons come loaded onto the device for pairing up with the contacts in your address book if you don’t want to use an actual photo. Even the low-battery indicator on the Sidekick chimes in a way that sounds cute.

But at the end of the day, this device is still not up to par with its competitors. In social circles where it’s considered cool, it might be worth buying. And if you have a separate phone, you can use the Sidekick 3 as a data-only device, though that means paying for, and juggling, two gadgets.

But the Sidekick 3’s poor phone, low-resolution screen and covered keyboard design left us unimpressed, even if it might be trendy. Our advice? Impress your friends with technology that works better for you, the user.

• Email: MossbergSolution@wsj.com