cell phone vs. smartphone

This might be too basic a question, but at what point does a cell phone become a smartphone? When it has a touchscreen? When it has Internet access? Or some otehr defining characteristic?

You can think of a smartphone like a miniature computer that can also place and receive calls. The simplest way to tell a cell phone apart from a smartphone is to determine whether or not the device has a mobile operating system.

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Smartphone vs Cell phone LetsGoMobile