In SharePoint, there is the ability to share with external people.
External people are people who do not have an Office 365 license in your organization's tenant.
This can allow for your users to work better with teams consisting of vendors, partners, customers, and so on. This can also lead to a nightmare if not properly controlled. Fortunately, these controls are becoming more granular and Microsoft is hearing the cries from IT. The sharing settings in the admin center is one of the newer additions to the set of controls you have available. The following screenshot illustrates what controls are available. Let's walk through them:
