The audience is one of the key options of the Announcement Feeds app. It has been added so that you could independently decide which group of users should be recipients of announcements.
This is important during creating announcements that only affect developers, graphic designers, PMs or any other in your team. If selected announcements are to reach all users, there is the "Public view permission" option, which speeds up the process of adding all user groups.
Available selection options:
a) Public view permission - with a single button, you can set the announcements to reach all users.
However, depending on previous arrangements, you can limit this group to users who have access to a specific project.
b) Groups - administrators can add users by groups they belong to in Jira.
Administrators set themselves to which groups of users they should reach announcements.
There is no limit in the number of groups added.
It is not possible to add groups if the option "Public view permission" is selected.