There are two types of channels: public and private. In order to promote transparency and to build your company’s knowledge base, we recommend opting to make channels public when at all possible.
A public channel is viewable to anybody on your team. They can see the channel when they browse channels, and they can join the channel if they feel that the topic is relevant to them. Public channels are those with a hashtag (#) in the title.
A private channel is only visible to the specific members of that channel– it will not appear in the list of a team’s browseable channels. Private channels are those with a padlock icon in the title.