Standard channels are available to all team members in Teams. Most channels are standard channels. If you need a smaller, specific audience for a particular subject, you can use a private channel.
Note: When you create a new team or private channel in Microsoft Teams, a team site in SharePoint gets automatically created. To edit the site description or classification for this team site, go to the corresponding channel’s settings in Microsoft Teams.
Let’s take a look at each type:
They’re open for all members and anything posted is searchable by others.
By default, all members of a team can create standard channels. Tenant owners can change this permission and limit channel creation and permissions to certain roles.
They’re for discussions that shouldn’t be open to all members, so you must be invited to join one to view it within a team.
By default, any team owner or team member can create a private channel and add members. Guests can't create them. Your admin can change this permission and limit private channel creation to certain roles.
Wikis, apps and bots, and scheduled channel meetings aren't supported at this time.
Files that you share in a channel (viewable on the Files tab) are stored in SharePoint. To learn more, see How SharePoint Online and OneDrive for Business interact with Teams.
Note: Files shared in a private channel are only viewable by the members of the channel and are stored in a separate SharePoint from the rest of the team's files.
Private channel meetings and calls
External guests can join a team's private channel meeting or Meet now call, but there are a few things to know.
They're only able to participate if a member of the private channel sends them a link to join the meeting, or calls them during the meeting to meet now.
During the meeting or call, they'll have temporary access to chat, files, whiteboard, notes, and the participants list (those not in the Outlook invite), but not after.
Create a channel
When you need to create one, see Create channels in Teams.
Change a team's data security classification in Teams
Manage channel policies
Manage the life cycle of private channels
How SharePoint and OneDrive interact with Microsoft Teams