G-Suite (formerly Google Apps for Business) is a service from Google providing independently customizable versions of several Google products under a custom domain name. It features several Web applications with similar functionality to traditional office suites, including Gmail, Google Groups, Google Calendar, Talk, Hangouts, Docs, and Sites. There is Google Apps Marketplace, an App "store" for G-Suite users. It contains various apps, both free and for a fee, which can be installed to customize the G-Suite experience for the user.
G-Suite also offers a 14-day free trial after which you must upgrade to the full version to fully enjoy the facilities.