Public cloud provides all of the applications and data storage for your business, but instead of owning and managing your own equipment and servers, the applications and data are hosted on servers and systems that are provided by the vendor.
Amazon, Microsoft, and Google are the primary ultra scale providers of cloud hosted Business Software suites, and their offerings are varied and provide virtually any form of software application for any line of business totally managed by them.
By providing the software applications and storage of all of the digital assets, these vendors provide a great way to have full featured and powerful applications, highly redundant storage, and availability from anywhere in the world you want to work, with a minimum of time and effort to maintain.
These Solutions are totally vendor provided, and their cost can be higher than a private cloud solution, as they are usually subscription based, and prices increase depending on the amount of applications, and the amount of storage that is being used to store all of your data.