What is a Smartphone?
A smartphone is a type of computer: a mobile device that fits in your hand (handheld) that works as a cellphone, but that also has functions that traditional cellphones wouldn't have, such as the ability to access the Internet, an operating system that allows the development and installation of new applications (called apps), the ability to display images and videos, an interactive screen (touchscreen) instead of physical buttons, the ability of take photos and record videos, among other functions.
Nowadays, dumbphone is a term we use to refer to a cellphone that isn't a smartphone.