The Apple iPhone uses a touch screen technology and is bound to propel a widespread adoption in the industry. However, not all touch screens are the same, and only Apple's iPhone allows the use of multiple fingers, according to Top Tech News on Friday..

Apple's iPhone is expected to have its share of imitators, and the phone is expected to introduce a wave of new products with a screen activated by the human finger. Touch screen displays are expected to jump from 200,000 units in 2006 to 21 million by 2012, with the bulk of those in mobile phones.

"This new user interface will be like a tsunami, hitting an entire spectrum of devices," predicted Francis Lee, the chief executive of Synaptics Inc., a company that makes touch sensors.

Despite the wave, Apple may retain a lead in its unique technology for awhile thanks to its software and patents. While about 38 million phones shipped in 2006 with some kind of touch screen feature, most use resistive technology. This technology has two layers of glass or plastic which can compress and locate the finger or stylus position on a thin metallic, resitive surface.

The iPhone uses the more advanced projected capacitive technology, and those don't need actual contact. Capacitive sensors behind the glass sense when the electrical field is disturbed. They can detect the finger from as far as 2 mm away. This allows for a more intuitive feel as the finger can glide across the surface. Since there's no resistive film, this kind of display can also be brighter.

"We've been doing touch screens for a long time, but this generation of touch screens is definitely breathing new life into the experience," said Todd Achilles, vice president of HTC American. "They're more accurate, more responsive, and you can get what you want to do on the first click."

In addition, the iPhone is the only device that can handle more than one finger at a time, as in the now famous "two pinch" used to resize graphics on the iPhone. Apple has a patent on this technique. While some manufacturers will try to emulate this feature, no other company has yet developed software to exploit that special gesture. As a result, not every mobile phone that touts a touch screen will have the same features as Apple's.

Even so, analysts believe that that the iPhone will be a strong catalyst for a new breed of hand held devices over the next few years, even if they've been left behind for now.