Smartphones are mobile phones that provide more computing power and connectivity beyond basic calling and texting. They combine camera phones and personal digital assistants. It is estimated that by 2014, over 1 billion people worldwide will use smartphones, including 45 million users in the US in 2011 and increased usage in China by 42% since 2009. While smartphones increase productivity and convenience by providing internet access, calendars, and social networks on the go, they can also make people anti-social and be expensive to purchase and repair. Common smartphone users include business professionals, students who can afford them, and most people aged 13 to 50+.