What you should know:
Cell Phone Types
Smartphones
At the top of today's handset pecking order is the smartphone. These devices typically have the most power and top-notch components such as processors, memory, screens, and connections to fast wireless data. By definition they run true mobile operating systems such as Apple's iOS, Google's Android, and Microsoft's Windows Phone.
Messaging or feature phones
Instead of popular mobile operating systems, these gadgets run proprietary software crafted by hardware manufacturers -- for example, Samsung or LG. Many feature phones tend to be made primarily for text messaging and e-mail, sporting full QWERTY physical keyboards.
Basic phones
There are plenty of people who have no interest in viewing full desktop-quality Web pages or running apps on their mobile device. Simply because, they just want a phone for making, well, phone calls.
Screen size
Large screens (4.7 to 5.5 inches)
Some gadgets such as the Samsung Galaxy Note 2 (5.5 inches) and LG Intuition (5 inches) push the screen real estate envelope to new heights, almost reaching a tablet level of functionality and girth. Keep in mind, however, that while devices with larger screen offers a bigger view, they are also harder to manipulate in one hand and can be uncomfortable to hold for long periods when you're making a call.
Medium screens (4 to 4.5 inches)
Phones in this middle category typically strive to balance the high degree of engagement and entertainment a larger display brings while still remaining practical. Motorola's Droid Razr M and Apple's iPhone 5 are good examples of this approach, offering large hi-resolution screens that users can grip with one hand and whose thumbs comfortably reach all portions of the display.
Small screens (under 4 inches) The swelling number of gargantuan smartphones hitting store shelves, compact cell phones are a shrinking segment of the mobile handset market. Some people still place portability highest on their list of phone features. Models like the HTC One V for example, are the most pocket-friendly, yet they manage to pack the hefty capability punch that Android can throw.
Processor
It provides the computing power to churn through tasks, like opening and running applications. A fast processor also has a big impact on overall performance, like how smoothly a phone handles flipping through menus and running home screens. Traditionally, clock speed, listed in GHz, has been the quick way to judge CPU prowess.
Camera
Though you might think that more megapixels is better, that's not always the case. You can get sharper images from a 5-megapixel camera than from an 8-megapixel shooter so it's better to concentrate on other specs.
There are other factors to keep in mind, though, such as the quality of the lens, which could aid the sensor by exposing it to more light. The sensor itself might also offer a lower pixel count, but be more sensitive to illumination, resulting in better performance under low-light conditions.
Many phones ship with fancy image processors -- such as those from HTC and Nokia -- which promise high image quality plus the horsepower to drive the camera and auto focusing systems faster.
Battery
Manufacturers have begun to recognize the critical importance of battery life and are squeezing greater capacity batteries into their phones. Typical phone batteries range from 1,700mAh capacities and go all the way up to 3,300mAh.
Manufacturers also list battery performance in terms of talk time, standby time, or by how many hours you can expect a device to perform tasks such as playing video and music.
Wireless carriers
Choosing a wireless carrier is perhaps the most difficult aspect of shopping for a cell phone. In many cases you don't have much of a choice since you're likely locked into a two-year contract and will pay a hefty early-termination fee if you cancel before your time is up. That said, when selecting a carrier, first on your list of criteria should be coverage. You'll want carrier with decent coverage in your home, at work, and all the places in between.
Screen technologies
LCD
LCD screens have come a long way from the alarm clocks and digital wrist watches of the 1980s. Today's smartphone LCDs offer HD resolutions of 1,280x720 pixels or higher and in sizes of up to 4.7 inches. Traditional weakness of LCD technology has been its use of an external backlight for illumination.
Retina
Apple uses what it calls Retina Displays in its latest iPhones. Essentially this is a clever marketing phrase to say the iPhone (both the iPhone 4/4S and iPhone 5) sport LCD screens with 326 pixels per inch . Of course as a way to describe screen quality, ppi isn't quite cut and dry. Samsung's Galaxy S III for example has a lower ppi of 306 but has a larger display and higher resolution (1,280x720, 4.8 inches).
AMOLED
Destined to replace LCD, active matrix organic light-emitting diode displays (AMOLED) use organic chemicals as the material to generate light. Much like neon light fixtures and plasma HDTV screens, AMOLED displays use OLEDs to create light when they're exposed to an electric current. Since they don't rely on backlights for illumination, AMOLED screens tend to have higher contrast and more-vibrant colors than LCDs.
Processors
Qualcomm Snapdragon
The current CPU smartphone king, at least for Android devices, is the Snapdragon family of processors. The 1.5GHz dual-core Snapdragon S4 powers high-octane devices such asMotorola's Droid Razr Maxx HD, Sony Xperia TL, and the Samsung Galaxy S III.
Apple A6
The A6 is Apple's latest wafer of processing silicon to grace the company's newest handset, the iPhone 5. So far all we know about the A6 is that Apple says it's twice as fast as the A5 chip that powered the iPhone 4S.
Samsung Exynos
The Exynos brand. Its most recent Exynos chip, the 1.5GHz quad-core Exynos, gives the Galaxy Note II its muscle and is one of the first phones to lean on four computing cores.
Operating system and software platform
iOS
Ever since the first iPhone, iOS has been the software powering Apple mobile devices. The current version, iOS 6, notably made waves when it dropped support for Google Maps in favor of Apple's own Map solution.
Android
Google's Android operating system has taken the lead both in terms of the number of products it powers and the number of individual users who rely on it. Android's freshest version, 4.2 Jelly Bean, only officially runs on the LG Nexus 4 but is sure to land on other phone models soon.
Windows Phone
The company's upcoming Windows Phone 8 mobile operating system is the most compelling yet with its new support for HD screens, multicore processors, and NFC.
BlackBerry
RIM, the makers of the once premier BlackBerry mobile communication devices, has been down on its luck lately. While many RIM owners in the U.S. have jumped ship and landed in either the Android or iPhone camp, the company hopes to reverse its fortunes with BlackBerry 10. BB10 is expected to provide a much improved interface, browsing, and application-friendly platform than RIMs aging BB7 products.
Phone features
NFC
Short for near field communication, NFC is a technology that has found its was into most current smartphone. NFC enables fast data exchanges between devices over short distances, just by tapping handsets together. While NFC is behind solutions such as Google Wallet mobile payments and Android Beam, it's not clear if there is strong consumer demand yet for NFC.
Quad-core processing
The CPU arms race once solely the domain of desktop and laptop computers has arrived to smartphones in earnest. First mobile processors with dual-core designs, or two dedicated processing centers on a single chip, will soon be eclipsed by silicon with four discrete cores.
Wireless charging
Wireless charging isn't a new ability. Toothbrushes and other household appliances have been able to perform this trick for years. It's been slow to catch on with phones, however, despite the greater need of constant power on the go. Hopefully the Nokia Lumia 920 will change things for the better. Not only is this Windows Phone 8 handset able to pair with accessories in a snap via Bluetooth aided by NFC, the gadget supports for inductive charging too.
Bluetooth and hands-free audio
Bluetooth is changing with the times, though, supporting new gadgets such as wireless stereo headsets and fitness trackers like the Fitbit Zip and Fitbit One. Additionally, Bluetooth version 4 promises to greatly improve battery life in supporting wireless phone accessories.
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