Most cellular phones these days are smartphones - they do more than just make calls. They are actually computers running an operating system that allows you to run apps for checking e-mail, surfing the web, plotting your travels, manage social media, playing games and watching video.
Smartphones also allow for creating a personal mobile hotspot, allowing you to use your plan's data allowance to get laptops and other devices online.
Apple iOS and Android are the two leading smartphone operating systems presently.