I have a question for people who know how websites work?

[Fifi]

Is this possible?
I’m writing a story about a group of popular girls who have a website they communicate with each other on and gossip . There are six girls and they are the only people who have access to the website because they are the ones who created it. They each have their own password and account. It is not like facebook where everyone can see your conversations. This website cannot be seen by anyone else except them. Are there websites that exist like that? What are they called?

[Lesus]

In facebook and some other sites you can create groups, where only members of the group can see what other members post.

[Minister of Truth]

there are sites like that; you could call it private network

[amontef]

Yes, they exist. There are intranets and VPN's (virtual private networks)