In 2016, you can easily make a group chat with almost any app such as iMessage, GroupMe, Facebook Messenger, etc. You make these groups so only you and a select group of people can communicate, and the group can be open or private. If the group is set to open anyone can invite themselves into it, but if the group is set to private, no one knows about it unless you add them into the group chat.
Most of the time these chats are made they're for good reasons, such as a family chats, friend or school chats or a work chat. You could find out what's for dinner, where to meet up or if someone could pick up a shift, but every once in awhile the chats are not used for good. The chats could be used to bash someone or something, or to plan something that could damage property or injure a person. When the chats are used for negative purposes, people make them private so no one can invite themselves into it. They keep them private in hopes that no one will ever see them and they won't get in trouble for what they said.
Everyone thinks that if they set the group to private no one will ever find out about it, or if they delete the messages the messages are forever gone. But, honestly, the messages never leave, and people will find out. IT techs can recover messages that were deleted from months to years ago; different phones are harder to crack, but it is doable. It doesn't matter if your text was a day old, or a year old; it will be recovered if you deleted it. So if you text negative things, make threats or talk about illegal things you can be caught. And if those messages are reported to the police, you can have charges pressed against you. And no one wants their life changed because of a text message or group chat.
Just remember, technology is great, but karma can come around if you don't use technology correctly. Nothing is private or secretive in this day and age. Is anything really worth messing up your future for? Make sure you are very careful what you put on social media, but also what you text in group chats. You may think you know someone, but you don't truly know anyone nowadays. Be careful with what you post and what you write because it could used against you. And change your life, and many other peoples lives, in a matter of seconds.