The ability to share your SharePoint sites and documents with people outside your organization is a very compelling capability in SharePoint Online. You are allowed up to 500 unique external users per month on the P-plans, and 10,000 for the M and E plans at no cost.
The people outside your organization are called External Users. External Users means users that are not either your or your affiliates’ employees, or your or your affiliates’ onsite contractors or onsite agents.
Over the years I've had so many questions as to what an external user can or can not do in SharePoint Online.
Here is a couple of the things they can do (have the rights to)
- External users can use Office Web Apps for viewing and editing documents. If your plan includes Office Pro Plus, they will not have the licenses to install the desktop version of Office on their own computers.
- External users inherit the use rights of the Office 365 customer who is inviting them to collaborate on a site. That is, if an organization purchases an E3 Enterprise plan, and builds a site that uses enterprise features, the external user is granted rights to use and/or view the enterprise features within the site collection they are invited to.
- An external user can perform tasks on a site consistent with the permission level that they are assigned. For example, if you add an external user to the Members group, they will have Edit permissions and they will be able to add, edit and delete lists; they will also be able to view, add, update and delete list items and documents.
- External users will be able to see other types of content on sites. For example, they can navigate to different subsites within the site collection to which they were invited. They will also be able to do things like view site feeds.
And here is a couple of the thing they cannot do (do not have the rights to)
- External users cannot create their own personal sites (what used to be referred to as My Sites). This means that they do not have their own SkyDrive Pro document library.
- External users cannot see the company-wide newsfeed. They also cannot edit their own profile, change their photo, or see aggregated tasks.
- External users do not add quota to the overall tenant storage pool (this is determined by licensed users only).
- External users cannot be an administrator for a site collection. However, you can designate an external user as a designer for your Public Website. This restriction also does not apply to scenarios where you have hired a partner to help you manage Office 365.
- By default, external users cannot access the Search Center and will not be able to execute searches against “everything” (cross site collection search)
Read more here.
- SharePoint Online: software boundaries and limits - link