SAN FRANCISCO -- Google is rolling out KitKat, the latest version of its popular software for smartphones and tablets with an ambitious goal: to get Android devices all over the world to run the latest version of the software. During a news conference in San Francisco, Sundar Pichai, Google's senior vice president of Android, Chrome and apps, said Google created KitKat to reach the next billion smartphone users by making the new software work well on low-end phones in addition to the pricier Samsung Galaxy and HTC devices. Emerging markets represent a major growth opportunity for Android. Pichai said Google is seeing "stunning growth" in places such as Brazil, Russia, Indonesia and Mexico -- three times the growth rate of the U.S. But manufacturers who make cheaper phones particularly for the developing world often use older versions of Android that don't use as much memory. Google is trying to address a key competitive disadvantage versus Apple called "fragmentation." Fragmentation makes it tougher for Android app developers to run the latest version of their services across all devices. By way of comparison, nearly two-thirds of Apple devices run the latest version of iOS software. So Google removed unnecessary services and reduced how much memory the operating system and applications such as Chrome and YouTube consume, making it possible for Android to run on devices that have 512 megabytes of memory, which are popular in much of the world. KitKat will be available on Nexus 4,7,10, the Samsung Galaxy S4 and HTC One on Google Play in coming weeks, the company said. This is the most aggressive push yet from Google to get the latest versions of Android on lower-cost devices that are spreading quickly in developing countries. It's unclear whether Google can get manufacturers and carriers to push software upgrades to existing Android devices, but Pichai said getting KitKat on new devices would quickly bear fruit for Google. Google on Thursday is also debuting the long-awaited Nexus 5 smartphone, which comes loaded with KitKat. The phone is available in black and white and goes on sale unlocked and without a contract on Google Play in the U.S., Canada, Britain, Australia, France, Germany, Spain, Italy, Japan and South Korea on Thursday. It will also be sold by Sprint, T-Mobile, Amazon, Best Buy and RadioShack. It's selling for $349 for the 16GB version and $399 for the 32GB version. With the Nexus5, Google is stepping up its competition with Apple's iPhone. "This is a cutting-edge device at an incredible price," Pichai said of the Nexus 5. Price is critical in developing markets, where people have less money to spend on devices. That's far cheaper than Apple's new iPhones. The iPhone 5c, the cheaper of the two new iPhones, costs $549 for a 16GB version that is unlocked and comes without a wireless contract. Google partnered with LG to develop the Nexus5, which Google says is slimmer and faster than previous Nexus phones. It has a five-inch HD display and optical image stabilization as well as a new HDR mode that automatically takes a flurry of photos and combines them to give the best possible single shot. With KitKat on the Nexus 5, Google unveiled some new features that it says brings Google power and smarts to Android. For example, swipe once on the Nexus 5 launcher to get to Google Now. Say "OK, Google" to launch voice search, send a text, get directions or play a song. Google is also experimenting with new technology that gives users results from both the Web and the apps on their phone when they search for information. Google is working with 10 mobile apps in the pilot program, including Flixster, Etsy, Trulia, Open Table and Expedia. It is to become available to more developers in coming months. Like it? Social ads turn users into unwitting endorsers Google banking on Android to help Google+ compete with Facebook Google+ adds new tools including making movies out of photos, videos