Circles in contact app what for?

Can someone very briefly explain what are circles in contcat app for?

I did create a circle, but what can I do with it?

The circles app has been fully integrated into contacts. It allows users to create their own ad-hoc “circles” aka “groups” of users to share and communicate with.

Learn more about circles at GitHub - nextcloud/circles: 👪 Create groups with other users on a Nextcloud instance and share with them

“Circles” enables you as a user to organize and group your contacts into “circles” where each circle represents contacts of some interest to yourself; such as: family, Friends, Soccer club, project A, customers, partners, etc. So, instead of enumerating recpients of every email or participants in every talk or shared document, you just choose the corresponding circle of people.

OK, thanks.
I tried to read some inofs abt it, but all say thae same, it is a feature to make kind of groups of contacts

I succeded to make a circle and add some of my users to it. But now? How can I let say send email to the circle?
(this would be my aim in fact)
The circle is not accepted by mail. So I have to select in mail again every user separately?

I tried in Talk, but also here a circle is not accepted as any kind of target.

Or which other apps can use circle?

exactly this I was expecting, but unfortunately this does not work. Email does not accept circle as mail destination, no recipients are included in the mail, therefore mail is not sent.

Yes it is integrated, but I could not find how to use it exactly so far.

I am not sure of whether emailing a circle is supported.

You just share the file or folder with the circle, or use whatever app Files/Talk, etc. to contact the circle.

Photo app Les Pas also support sharing albums to circle