What does "comment internally" actually mean in JIRA Service Desk?

[Ji]

In JIRA Service Desk projects, comments are segregated by internal vs external visibility. Meaning that I am able to select whether I want to Share with customer or Comment Internally.

Which users are able to see comments that are specifically marked as internal?

I couldn't find proper documentation describing this feature.

[Nic Brough [Adaptavist]]

Share with customer makes the comment visible to everyone who can see the issue/request.

Internal comments do not appear on the requests, so a customer can not see them.

[William Raendchen]

Internal comments are not shown on the portal view of the issue. However, everyone who can see the internal version of the JIRA ticket can see both internal and external comments!

Internal = "Everyone who uses JIRA and has access to this issue in JIRA itself. But not displayed on the portal view"