A Chat is a conversation between one or more Blink users. They are completely private between members and cannot be discovered.
Blink users prior to June 2018 may additionally have something called Channels. These are a retired feature of Blink and no longer available.
Things to remember about chats on Blink
Any member of a chat can add a new member, but only administrators can remove people.
Only administrators can change chat details such as the title, description or icon.
When someone leaves a chat, it will disappear from their chat list. They lose access to it entirely including all content shared in it and the conversation history. To rejoin they must be re-invited by an existing member.
When someone joins a new chat they can see the entire history. User's are able to mention other user's in their messages to ensure they receive a notification and don't miss crucial information. As a new feature, user's are also able to use a GIF picker, to choose a GIF perfectly suited to the message.