Reading up on iPhone, iPod touch, iPad, or Apple TV and wondering what all those data specifications and cellular networking terms mean? From 2G to WDCMA, 802.11 to Bluetooth, we’ve got you — and every wireless term we can think of — covered below!

For even more iOS and Apple-related terms see our complete iPhone and iPad glossary. And as always, if we’re missing anything, add additions and corrections in the comments below!

[Special thanks to The Cell Phone Junkie, Mickey Papillon for help compiling this list!]

• 2G: Second generation data networking used by iPhone and iPad. Think of this like old-fashioned dial-up modems. (see EDGE.)

• 3G: Third generation data networking used by iPhone and iPad. Think of this like base level broadband Internet (cable/DSL). 3G is symbolized on the iPhone and iPad by 3G next to the carrier logo. (see HSPA and EVDO.)

• 4G: Forth generation data networking. Also a marketing term used by Sprint for WiMax, T-Mobile for HSPA+, and AT&T for HSPA+. Think of this as super-fast broadband Internet (cable/fiber). (See HSPA, HSPA+, LTE)

• 802.11: The standard used for WLAN (Wireless Local Area Network), typically referred to as Wi-Fi, connections on iPhone, iPod touch, and iPad. While older models supported only 802.11b/g, 2010 models added support for the faster, longer range 802.11n standard. (Only iPad supports 802.11n on the clearer 5Mhz frequency, however.)

• A2DP: Advanced Audio Distribution Profile is a Bluetooth standard used to transmit and receive stereo music. Added to iPhone, iPod touch, and iPad in iOS 3. It’s what lets you send iPod music to your wireless stereo Bluetooth headset.

• Airplane Mode: A Setting on iPhone and iPad that turns off all radios, including cellular voice, data, Bluetooth, and Wi-Fi. Called Airplane Mode because these radios are typically required to be turned off while on an airplane.

• AVCTP: Audio/Video Control Transport Protocol allows for the transmission of basic music controls between devices and accessories. Only properly supported for iPhone, iPod touch, and iPad since iOS 4. It’s what lets you play, pause, fast forward, rewind, and skip through music and video via wireless stereo Bluetooth headsets.

• Bluetooth: Named after a Danish King (seriously), Bluetooth is a wireless technology used for exchanging short-range (under 30-feet) data between electronic devices. iPhone, iPod touch, and iPad support Bluetooth 2.1 + EDR (Enhanced Data Rate) for better security and simpler pairing. Apple currently supports Bluetooth for wireless phone headsets, stereo headsets, keyboard connections, and data tethering.

• CDMA: Code Division Multiple Access is an underlying network standard and the common abbreviation for CDMA2000, the technology used by Verizon and Sprint in the US.

• CDMA2000: The networking technology used by Verizon and Sprint. A single CDMA tower typically has a longer range and thus provide greater coverage than a single GSM tower.

• EDGE: Enhanced Data Rates for GSM Evolution, also called 2G, 2.5G or 2.75G depending on the data speed, is an older data network used by carriers like AT&T. The original iPhone was EDGE-only. Current iPhones can use EDGE when 3G is not available (or on T-Mobile in the US where 3G frequencies aren’t compatible). Real world EDGE speeds max out around 150Kbps and do not allow simultaneous voice and data (calls will not come through while using EDGE data). EDGE is symbolized on the iPhone and iPad by the uppercase letter E. iPhone 4 and iPad support EDGE on the 850, 900, 1800, 1900 MHz frequencies.

• EVDO: EVolution Data Optimized is the 3G networking technology used by CDMA carriers like Verizon. EVDO Rev A can achieve speeds up to 3.1 Mbps but cannot handle simultaneous voice and data, but does allow incoming calls to come through during an active data session. (Answering an incoming call will shut off the data connection.) EVDO Rev B can handle voice and data but is not planned for deployment by any US carriers. iPhone 4 supports CDMA EV-DO Rev. A on 800, 1900 MHz.

• GPRS: General Packet Radio Service is the oldest and slowest form of data networking available to GSM iPhones and iPads. Data rates are typically below 50 Kbps. GPRS is symbolized on the iPhone and iPad by the lowercase letter o.

• GSM: Global System for Mobile communication is the underlying technology standard used by AT&T and T-Mobile in the US and the majority of carriers in Europe and around the world.

• HSPA: High Speed Packet Access is a fast form of 3G data networking. The iPhone and iPad support HSPA up to 7.2 Mbps (AT&T currently supports up to 14 Mbps in some areas). Typically split into HSDPA (download) and HSUPA (uplink/upload). iPhone 4 and iPad support UMTS/HSPA on the 850, 900, 1900, 2100 MHz frequencies.

• HSPA+: Enhanced High Speed Packet Access is a faster form of 3G data networking, now called 4G in T-Mobile and AT&T’s marketing. Apple will support HSPA+ in 2011. Top speeds can reach 56 Mbps. Bell and Telus currently offer 21 Mbps HSPA+.

• LTE: Long Term Evolution is a 4G networking technology currently being deployed by Verizon and scheduled to be deployed by AT&T, Canadian carriers, and others. Theoretical speeds are measured in the hundreds of Mbps but initial implementations haven’t reached those yet. Likewise initial implementations only use LTE for data while future versions could be pure IP-based for both voice and data. Neither iPhone nor iPad yet support LTE.

• Personal Hotspot: Introduced with the Verizon iPhone and iOS 4.3 it replaces Tethering and, on iPhone 4, adds the ability to share cellular data over a Wi-Fi connection with up to 5 additional devices. Availability will depend on carriers and some may/will charge extra for it. Think of it as a built-in MiFi or the ability to turn your iPhone into a mini mobile Wi-Fi router.

• Tethering: Sharing your iPhone’s cellular data connection with your laptop via USB (dock cable) or wirelessly via Bluetooth. Available since iOS 3 though AT&T only chose to support it with iOS 4. Not available on all carriers and some carriers charge extra for it. Replaced in iOS 4.3 with Personal Hotspot.

• UMTS: Universal Mobile Telecommunications System is a 3G, transitioning to 4G networking technology. WCDMA (including HSPA) is part of UMTS.

• WCDMA: Wideband Code Division Multiple Access is a UTMS technology which, while easily confused with the CDMA network used by Verizon, is actually associated with GSM networks like HSPA.

The S stands for speed, and the 3G stands for the third generation, HSPA (High Speed Packet Access – wikipedia link) data network, which is also supposed to bring broadband-like speed to your iPhone’s internet connection. When you’re on the 3G network, you can tell by the little 3G symbol at the top of left of your iPhone’s menu, right beside the signal strength bars and the name of your carrier (AT&T, Rogers, O2, Orange, etc.).

There are several other symbols your iPhone might show instead of 3G, however, depending on the type of connection and reception available in your area and sometimes specific spot.

If you don’t have a 3G connection, whether your area doesn’t support it or you’re just indoors or behind an obstruction that’s preventing it, your iPhone might default down to a 2G connection, known as EDGE, (Enhanced Data rates for GSM Evolution – Wikipedia link). That’s the little E symbol, and If we keep the same analogy, this is older, slower technology — dial-up to 3G’s broadband.

If you’re getting an E and you really think you should be getting 3G, try going to the Settings Icon and toggling Airplane Mode on and off. That should force your iPhone to re-connect with the network and give you the fastest speed available. Sometimes even moving to a different, less obstructed spot can make a big difference.

If even EDGE isn’t available, the iPhone will still try to connect via GPRS (General Packet Radio System – Wikipedia link) an even older, slower 2G protocol shown with an O symbol (for outside chance?). To stretch our analogy as thin as this signal, GRPS would be the ancient 24K modems.

Of course, if you have Wi-Fi enabled and connected, you’ll get the Wi-Fi fan symbol instead.

If you’ve turned all the radios off and gone into “Airplane Mode”, you’ll get the little airplane symbol and absolutely no connection to the internet whatsoever. (Turn Airplane Mode off — and your connections back on — via the Settings icon on your home screen.)

And yes, you can turn on Airplane Mode and still re-enable Wi-Fi if you really want to.