The Visibility setting determines who sees the segment in their list of segments.
Unlisted—these segments are visible only in the owner's list of segments. This prevents segment lists from becoming unnecessarily cluttered. This is the default setting.
Anyone in the environment—these segments are listed in everyone's list of segments.
It is important to understand that the Visibility setting doesn't affect general access to segments.
Regardless of configured visibility, any segment can be accessed with storage:filter-segments:read
permission. This guarantees that even unlisted segments that may be referenced in a shared notebook, can be used by anyone having access to that notebook.
For more information on segment permissons see IAM policy statements.