What is the definition of a smartphone, i.e before anything else what is it? See detail.

Here ya go—
“a mobile phone that performs many of the functions of a computer, typically having a touchscreen interface, Internet access, and an operating system capable of running downloaded applications.” Oxford Dictionary

I would say it’s a handheld computer with an operating system capable of executing other programs that uses a touch-screen user interface, and it also happens to make phone calls.

I’ll keep reading. So far it’s one for each.