Office 365 Groups is a service developed with collaboration in mind. It works with the Office setup tools you use already so you can collaborate with your teammates when writing documents, creating spreadsheets, working on project plans, scheduling meetings, or sending email.
For complete application visit office.com/setup
What is Microsoft Office 365 Groups?
Groups in Office 365 let you choose a set of people that you wish to collaborate with and easily set up a collection of resources for those people to share.
Resources such as a shared Outlook inbox, shared calendar or a document library for collaborating on files.
Different teams may prefer to work different ways and Office 365 has the tools to enable collaboration in whatever form your teams prefer.
for more details, visit the official website of Office : www.office.com/setup.