Viewer is a specific permission available at the project level.
Viewers are a way to bring members of your team, such as engineers or C-level executives, into your Project. You can even invite external stakeholders, such as consultants or customers.
Inviting Viewers to your Organization
To invite new Viewers to your Organization, go to Team Management in your Account Menu to invite new team members.
Selecting Member Access will allow you to add users to your Organization. Once they've accepted the invitation, you'll be able to add them to specific projects as Viewers.
Adding Viewers to Projects
Once you've added some members to your Organization, you will need to choose which Project(s) to add them to within the Team Member menu of that project.
Managing Viewer Permissions
Once you've added your user to a Project, you'll select their permission status. Viewers are able to view your Project, but can't make any changes.
You can easily promote users from Viewer to Limited Contributor in the Team Members menu within projects.
This is also where you can remove Viewers, for example when their involvement in the Project has ended.
Learn more about Organization Permissions here.