Apple on Wednesday introduced its new iPhone 5, a lighter, thinner and more powerful version of its iconic mobile device.
Apple chief executive Tim Cook called the launch "the biggest thing to happen to iPhone since the iPhone."
At a packed launch event in San Francisco, Apple marketing chief Phil Schiller said of the new iPhone: "It is an absolute jewel. The software and engineering that went into this product is the most challenging our team has ever taken on."
Apple will start taking orders for the phone Friday and begin shipments September 21 in the US, Canada, Britain, France, Germany, Australia and Japan, and would be available in 100 countries by the end of the year. Pricing for US customers will start at $199.
The introduction has been among the most keenly anticipated in the tech world, with rumors and leaks over several months about the new device from the biggest company in the sector.
"It is the thinnest iPhone we have ever made, it's the world's thinnest smartphone and weighs just 112 grams," just under four ounces, Schiller said.
"It is 20 percent lighter than the iPhone 4S."
Schiller said the new, taller iPhone, made of glass and aluminum, features a new design to nestle in one's palm to naturally align with thumbs and works on the faster mobile Internet networks known as LTE.
"When you carry your phone it should fit beautifully in your hand, that is just how we designed iPhone 5," he said.
"Everything you do looks gorgeous on this beautiful widescreen display," he said, describing the so-called Retina high-definition four-inch (10 centimeter) display used on other Apple devices.
The new device features Apple's own new A6 processor, which according to Schiller doubles the speed for loading Web graphics.
He also said the phone would address consumer complaints by extending battery life, to eight hours use with mobile phone and browsing and 10 hours if Wi-Fi connections are used.
The iPhone 5 includes an improved camera with "new dynamic low-light mode," and "a precision lens alignment," Schiller noted.
Apple has also installed its own mapping software, upgraded its voice-activated assistant known as Siri and incorporated Facebook in the iOS software.
Analysts expect Apple to sell tens of millions of the new iPhone in the coming months, luring in smartphone buyers who have been waiting to upgrade.
"This iPhone 5 will turn out to be Apple's biggest home run yet. This will be the biggest and most successful Apple iPhone launch so far," independent analyst Jeff Kagan said.
Morgan Stanley analyst Katy Huberty said it is possible Apple may ship between 48 million and 53 million iPhones in the fourth quarter and "up to 266 million" in 2013.
She said the company could sell eight to 10 million in the third quarter, or in just the opening days it becomes available.
Apple has fierce customer loyalty and has been rapidly gaining users, but has lost market share to the faster-growing segment of smartphones powered by Google's Android operating system.
Smartphones powered by Android software continued to dominate with 52.2 percent of the US market in the past months, but Apple's iOS was the second most popular smartphone platform with 33.4 percent, comScore reported.
Samsung mobile phones remained the most popular in the United States with 25.6 percent of the market, but third-place Apple gained ground to claim 16.3 percent as of the end of July, according to comScore.
Apple is engaged in litigation with Samsung over patent infringement and is seeking to ban US sales of some Samsung devices after a major court victory in California last month.
Nicholas Carlson of the website Business Insider said the new iPhone launch represents "the most pivotal moment" for the sector.
"Companies that are, collectively, worth a trillion dollars -- Samsung, Google, Amazon, Microsoft and more -- have bet billions of dollars building competitors to the iPhone," he said.
"Today, they find out if Apple has once again leapt way ahead of them, or if finally, the battleground is growing even."
Apple shares, which hit record highs this week and extended the company's position as the world's most valuable firm, edged up 0.7 percent to $665.36 on the news.
Apple is widely expected to launch a smaller version of its market-leading iPad tablet computer later this year.