At first glance, one might initially think that Guest Access and External Access may be referring to the same thing. However, there are actually two separate policies which can be adjusted based on organization's needs. Starting with External Access, this enables external users and organizations to find, call, and interact with users within another organization. External users have no access to an organization's resources and is mostly used just for communication purposes. By default, once External Access is enabled, an organization can communicate with all external domains. Organizations can either disable external sharing or specify which domains they would like to include or exclude, thereby giving more control over the external access policies. 

Guest access, on the other hand, is a little bit different as guests can be provided nearly all the same capabilities as an actual member in the organization. Guest users are actually added into an organization's active directory and can communicate and collaborate with a Guest user as they would with any other team member. And since they are directly invited to a team, they are given access to files, much like members have access to. For specific details on whether you're looking for External or Guest Access, I have linked the page that clarifies the specific differences between each in the documents below.

Now that we understand each type of Access, let's talk about some specific details and best practices of each. External Access should be considered when organizations have users that need to communicate with users from multiple different domains and want to use Teams to do so. External Access has functionality that allows organizations to specifically allow or block domains and depending on how the organization sets this up, determines how External Access will function. For example, if an organization blocks a specific domain, then all other domains will be allowed. On the other hand, if an organization allows a specific domain, then all other domains will be blocked. We'll go over this a little bit during the demo later on. Now, if External Access is purely for communication with external users, remember that Guest Access takes things a little bit further than that. Guest Access should be considered when you have users outside of your organization that need to communicate and collaborate with your internal users. But what exactly is a guest? Well, typically a guest would be someone like a partner, a vendor, a consultant, or just an external user whom has a need to collaborate with your internal users.

And like I mentioned earlier, once a guest user is invited, they are added into an organization as your active directory. This allows organizations to manage guest users with the same security and compliance policies they use to manage their own internal users. And for added security, organizations can specify exactly what kind of access guest users have by utilizing sensitivity labels and restricting guest users from accessing highly sensitive data or resources while still allowing them access to the necessary resources. Now that we understand each type of access, let's showcase how to adjust External and Guest Access settings.