The iPhone's Hidden Sensors

While the iPhone won't actually do all of your thinking for you (this is, after all, an interactive device and not a robot), it certainly makes life a lot easier, especially if you're used to a cell phone that just makes calls. The device is designed to create a seamless and natural user experience. It can feel so natural, in fact, that you might not even notice some of the more advanced features.

Ambient Light Sensor

The ambient light sensor, located inconspicuously near the phone's ear piece, detects the amount of light in your surrounding environment and adjusts the screen's backlight accordingly. This serves a couple of important functions: First of all, it makes the viewing experience more comfortable and eliminates the need for you to go through settings menus to adjust it yourself. Second of all, it helps conserve battery life by only using the amount of backlight that's necessary.

If you'd prefer to control the iPhone's backlight yourself, you can do so by tapping Settings>Brightness and turning Auto-Brightness off. You can also manually adjust the level of brightness by dragging the slider from left to right.

Proximity Sensor

Have you ever been on a phone call and accidentally pressed buttons (or terminated the call) with the side of your face? The proximity sensor, which is located near the ambient light sensor, disables the iPhone screen when you bring the device to your ear (i.e. talk on the phone), thereby eliminating the possibility of accidental hang-ups.

The Accelerometer: A Built-In Motion Detector

One of the coolest features of the iPhone is its use of accelerometer technology. To many people, that’s a six-syllable word that doesn’t mean much but certainly looks and sounds impressive. Before you start imagining that the iPhone has a built-in matter transport device akin to something you may have seen on Star Trek, perhaps a few words of explanation are in order.

The accelerometer is the internal device that detects motion. It’s the same technology that’s implemented in the Nintendo Wii remote control, which revolutionized gameplay and one-upped the traditional joystick in terms of ease of use.

The iPhone’s internal accelerometer is what’s responsible for the nifty feature you’ve probably seen displayed a time or two, where simply turning the iPhone from vertical to horizontal orientation (or vice versa) switches the display accordingly. This is particularly handy if you’re viewing a website or watching a video and want to switch to widescreen or landscape view. A horizontal view also lets you access additional scientific functions on the calculator, which is probably the least-heralded iPhone update, but certainly one of the most useful for many people.

Remove iPhone’s SIM Card with Included Ejector Tool

An awful lot of hullabaloo has been made of the iPhone’s SIM card, with questions abounding. Since the iPhone’s battery can only be removed by a trained (thus paid) professional, does the same go for the SIM card? What happens if you have an iPhone warranty issue and have to send your phone in for service? Surely you can’t be without phone service for that long, and nobody expects you to.

The iPhone allows you to easily remove and replace your own SIM card. It even comes with its very own SIM ejector tool, rendering that paperclip in your top desk drawer all the more obsolete.

All you have to do is firmly insert the end of the SIM ejector tool into the tiny pinhole of the SIM tray until the tray pops out. Remove your SIM card from the ejected tray and you’re good to go. Removing the SIM card is also useful if you want to loan your iPhone to a friend without worrying that they’ll go hog-wild downloading apps you don't need.

Contrary to the claims of naysayers, your iPhone SIM card can be inserted into another phone to allow you to make calls—just don’t go expecting the iPhone’s functionality.

The iPhone Ringer Switch

One of the great curses of owning a cell phone is its tendency to make random noises at any given moment, especially when silence is of utmost importance. Ever received angry looks during a movie? Or how about receiving full-volume notification of an incoming text during a job interview? Nothing screams "unprofessional" more clearly than a poorly timed iPhone alert.

Luckily, there's a handy ringer switch right above the volume control on the phone's left spine. Flip it toward you to turn the ringer on and away from you to turn it off (when the ringer's switched off, you'll see an orange dot on the switch).

When the ringer is on, the iPhone will play all sounds, including alerts and sound effects. When it's turned off, only the alarm clock will sound. Turning the ringer on or off will not affect the vibrate function; if you want to shut off this function, you can do so in Settings>Sounds.

The Volume Control Buttons

Your ears are a sound investment. You don’t have to be an audiologist to know that blowing out your eardrums is a bad thing that could lead to problems later in life. The fact that your iPhone houses an integrated media player is ample reason for you to approach slapping on a pair of earbuds with great care.

Volume levels for your iPhone are easily set with the buttons located on the left spine of your phone. Easy enough—the top button turns the volume up, the bottom button turns the volume down. When you’ve got your earbuds plugged in, these buttons control what you hear through them (including phone calls and alerts). With the earbuds unplugged, the buttons control the phone’s ringer, alerts, and sound effects.

If you want to make sure that you don't go overboard on the volume, or if you have children whose ears you want to protect, you can set a maximum volume in Settings>iPod>Volume Limit.

The volume-level buttons can also be used to silence a call in the event that you’ve gone and done it again by leaving your ringer cranked all the way to 11 when you really shouldn’t have. If this unfortunate circumstance should arise, you don’t have to use the volume control to turn the ringer down incrementally—just press either of the volume buttons once to silence the phone. If you want to reject the call and send it straight to voicemail, just press the same button a second time.

The iPhone's Multi-Touch Technology

The iPhone’s touch screen is without a doubt its greatest appeal. Having taken a giant leap forward in terms of ease of use and plain old convenience, the iPhone has set the standard by which all future smartphones will be (and are being) judged. Where other touch-screen phones can only react to one touch at a time, the iPhone contains features that actually require and invite multiple taps on the screen.

One of the most impressive of the multi-touch functions is the zoom feature, created for optimal use on websites and with pictures. In order to zoom in on a certain point, simply place your thumb and forefinger on the screen in a pinching gesture, then drag your fingers apart to zoom in. To zoom back out, just pinch your fingers back together.

The circuitry underneath the screen is complicated enough to make you wish you hadn’t asked about it in the first place; however, the sleekness of the design and the flexible transparent surface just on top of the iPhone glass screen lets you easily forget you’re dealing with a delicate piece of equipment. For all its benefits, the iPhone is not indestructible, and Apple’s one-year iPhone warranty doesn’t cover accidental damage. So, until someone invents an anti-gravity app, it might be wise to invest in third-party iPhone insurance.

iPhone Takes the Comfort of Home to New Levels

While it might seem like one of the less exciting features of the iPhone, the Home button is one of the most versatile.

• It works to wake the iPhone from sleep. To get the phone to come back to life (after you've hit the Sleep/Wake button to put it on standby), simply press the home button and drag the slider on the screen. The slider is there to keep you from accidentally unlocking your phone when you shift positions (or jam your fists into your pocket or purse a little too vigorously while rifling for change).
• It will get you out of any application, no matter which area of the application you're in, and return you to the home screen. Don't look for any kind of exit button in any applications—the Home button makes it unnecessary.
• It can be programmed to launch the iPod, Camera, Search, or Favorites functions with a double-tap. This option can be found under Settings>General>Home. With the 3GS, the Home button can be programmed to work with the phone's accessibility functions, such as the VoiceOver screen reader.
• It acts as a save button when rearranging your home screen(s). To move your applications around, tap any icon and hold your finger there until all of the icons start to wiggle. Move them around, and when you're finished, press the home button to save your changes and make the icons sit still.

Roll Your Media Devices Into One With a Built-In iPod

One of the most overlooked and potentially undervalued aspects of the iPhone is its built-in iPod, a feature that could be the most potent selling point for many people. Forget touch screens. Forget ambient light detectors and accelerometers. Many people are sold simply on the fact that the iPhone eliminates the need to carry around two separate devices.

Apple has even managed to throw some interesting twists into the whole iPod listening experience.

• The shake to shuffle feature lets you skip to a song with a simple flick of the wrist.
• The new-and-improved scrub feature allows you to fast-forward or rewind to certain points in an audio file and control the speed at which this happens. This is particularly useful for podcasts and audio books.
• The iPhone’s iPod also incorporates Genius, an automatic playlist creator that selects songs in your iTunes library by musical genre and creates unique mixes.
• You can also purchase movies from the iTunes store on your iPhone and either watch them on your phone or through an external display (with the appropriate A/V cables).

Taking Pictures With Your iPhone Is a Snap

With all the bells, whistles, and frills hidden just beneath the sleek surface of the iPhone, it only makes sense that it would come with a built-in camera. While cameras have become a pretty standard feature on cell phones and smartphones, Apple has come up with ways to set itself apart.

• If it isn’t enough that the iPhone makes it incredibly simple to snap a picture and instantly email or message it to another person, it also integrates other features in an innovative way. Every photo you take is automatically tagged with your geographical coordinates, thanks to GPS (the standard feature) and the built-in compass (the not-so-standard feature).
• The iPhone 3GS also comes with a handy "tap to focus" feature that allows you to focus on a specific object by tapping it on the preview screen. The phone automatically adjusts the exposure.
• The camera in the iPhone 3GS can also record video. You’re even given the option of editing out unwanted sections of video footage by utilizing the "trim" feature, which is activated by tapping the screen during video playback.

The Liquid Damage Indicator - How to Tell if Your iPhones Been Drinking

Apple offers a limited manufacturer’s warranty for the iPhone that doesn’t cover theft, breakage, or liquid damage. This makes it especially important to: a) Make sure you don't accidentally take your iPhone for a swim, and/or b) purchase liquid damage insurance.

If you ever find yourself in the market for a used iPhone, checking for signs of previous liquid damage could save you a good amount of time, money, and disappointment. So how do you know? All iPhones and iPods built after 2006 carry what’s called a built-in Liquid Submersion Indicator, which is just the manufacturer’s fancy way of saying “get it wet and we'll know about it.” The indicator can be found by looking directly into the iPhone’s headphone jack. The 3G and 3GS models have an additional liquid indicator in the dock-connector housing. When in pristine condition, these areas will appear white or silver. If your iPhone’s taken a big drink at any point during its existence (or even been slightly wet) these areas will be red or pink.