Smartphones have evolved enormously in the last decade, going from physical keyboards and 400 mHz processors to quad cores and 4.3 inch touchscreens in 2011. The smartphone industry jumped a few steps when the iPhone was released on the market and since then manufacturers have been competing to bring the newest and most powerful hardware to users. In just 4 years the industry has evolved as much as in 10 and at this pace we will end up with phones and tablets as powerful as laptops or computers.
Those from TechKing they made an infographic showing the evolution of smartphones and I think it's interesting to see.
