Permissions are based on 4 different user roles; owner, co-owner, client, and contributor.

1) Owner role:
Each workspace can only have one owner which is usually the person who created the workspace.

2) Co-owner role:
Co-owner share the same level of access as the owner, and only the owner or co-owner can invite other co-owners.

3) Client role:
Client is a default role designed to only give clients access to things that are assigned or related to them.

4) Contributor role:
Contributor is a custom role designed to be as flexible as possible to fit your needs. You can create as many custom roles as you want, each with their own level of permissions.

For example, you could create a custom role for teammates with access to all projects by default, and create another custom role for contractors with access to only projects they are added to as members.

From Settings > Permissions you can access the full list of roles.