Work with Channels

Channels fall just below teams in the Slack hierarchy, letting team members communicate in a topic-based structure. I would wager that despite a lot of communication in conversations, the vast majority of interaction in Slack happens in channels.

A channel has either a hash or a lock icon before its name wherever it appears in Slack, which respectively indicate whether a channel is public or private. Private channels appear in your list only if you’re a member; even team admins don’t see private channels unless they’re a member.

Every Slack team starts with two channels populated by the system: #general and #random. From there, teams chart their own course.

In this chapter, I’ll explain how to join an existing channel, how to Create a Channel, and how to Interact in a Channel.

Join a Channel

As noted just above, Slack has both public and private channels. You can search through a directory for public channels to join, or you can be invited by someone who is part of a channel already. You have to be invited to a private channel.

Find and Join a Public Channel

You can find available public channels in several ways, depending on the Slack app you’re using:

Someone can also invite you to a channel, which I discuss later, in Invite Others to a Public Channel.

Join a Private Channel

To join a private channel, someone in the channel has to invite you, either when they create the channel or at a later point. (If you create the channel, you’re obviously already a member.)

Slack notifies you when you’ve been invited in a subtle way: the private channel’s name appears in the sidebar’s channel list, highlighted in bold and with a number indicator (Figure 91).

**Figure 91:** A private channel appears in the sidebar, in bold type.
Figure 91: A private channel appears in the sidebar, in bold type.

It’s not so much an invitation as a command performance. You’ve already been added to the channel, and selecting it in the sidebar just reveals a message a about how private channels work (Figure 92). You have to Leave a Channel to stop being a member of it.

**Figure 92:** Slack lets you know about the private channel to which you’ve been invited, and lets you avoid seeing this dialog in the future if you check the box.
Figure 92: Slack lets you know about the private channel to which you’ve been invited, and lets you avoid seeing this dialog in the future if you check the box.

View Your Channels

After you’ve joined a channel, it appears alphabetically within one of these groupings in the main sidebar:

In the desktop and Web apps, you may see a red badge to the right of a channel’s name in the sidebar. The number in the badge indicates how many unread messages contain your handle or name, or any of your highlight words.

Starring a Channel or Conversation

To star a channel or conversation, first select it in the sidebar. Then, in a desktop or Web app, hover over the name in the toolbar and click the star icon that appears (Figure 94). (For an unstarred channel, the icon appears only when you hover in the toolbar, and looks like ; when you hover directly over it, it looks like .) In a mobile app, tap the channel or conversation name and tap Star This Channel/DM.

**Figure 94:** Hover over the star icon and then click it.
Figure 94: Hover over the star icon and then click it.

Your new favorite appears alphabetically in the Starred category, which lists channels at the top and conversations below. To un-star a channel or conversation, click its star icon again.

Create a Channel

What do you want to talk about today? Or every day? Or some days? Channels let you organize conversation into topics, but a channel doesn’t have to persist forever.

Guests cannot create new channels, and your team’s admins get to decide whether full members may create channels. Most teams will likely agree among themselves to establish a basic set of channels, sometimes proportionate to the number of people. With 1000 people in a team, a few channels likely won’t be enough. For 10 people, it’s overkill to have 50 channels.

Channels can be public or private. Public channels are searchable by every full member in the team and any full member can join a public channel. In contrast, private channels and their contents are restricted to those who are invited by members of the channel.

Before you create a private channel, make sure that what you want isn’t a conversation. Conversations are private, conducted as direct messages, and they can be one-on-one or within a group of up to nine members. Conversations generally work well for short-term topics, like planning a meeting or getting ideas for solving a timely problem. They also work well as an exact analog of instant messaging with a colleague for real-time talking, as a replacement for a different instant-messaging (IM) service, such as SMS, WhatsApp, iMessage, or Google Chat.

Let’s start with why it makes sense to create more channels. After that, I give directions for how to Create a Public Channel and how to Create a Private Channel.

Why Make New Channels

Creating more channels can solve these problems:

Create a Public Channel

The mechanics of creating a public channel are simple:

**Figure 96:** In a mobile app, you name a channel while you make it.
Figure 96: In a mobile app, you name a channel while you make it.

That’s all there is to creating a channel, but each of the three actions—naming, inviting, and entering a purpose—deserves a little more discussion.

Name Your Channel

You can name a channel anything, so long as it conforms to Slack’s rules: no more than 21 characters, all lowercase, and no spaces or periods. But consistent naming will help your group if it has more than a handful of channels. You’ll run into the 21-character limit quickly if you’re too descriptive, which makes it hard to differentiate channels if too many are created without a naming scheme.

Remember that channel names appear alphabetically in the various sidebar lists and autocomplete menus. A scheme that takes this fact into account will help other team members find the right channel quickly. For instance, if your team has multiple departments, it might use a prefix, like acct for accounting and edit for editorial. Then instead of #general-accounting and #general-editorial channels, which sort by “general,” you’d see #acct-general and #edit-general.

Invite Others to a Public Channel

It’s a party! Let’s fill the room! You can invite other people to a public channel by working in a dialog or by typing a slash command:

**Figure 97:** The invitation dialog lets you pick people in a variety of ways.
Figure 97: The invitation dialog lets you pick people in a variety of ways.

To check who has joined a channel, in the desktop and Web apps, select the channel in the sidebar and then click the Channel Details button on the toolbar. In the mobile apps, tap the channel name at the top of the messages list, and then tap Members.

Describe Your Channel

Slack offers two independent ways to give a channel a sense of identity: its purpose (a general description of its goal) and its topic (what it’s focusing on today). Any member can revise either. See Set the Purpose and Set a Topic, both later in this chapter, for more.

Create a Private Channel

To start a private channel, use the same process described above (start by clicking the Add button next to the Channels heading in the main sidebar), but flip the Public switch to Private. It’s easiest to invite members when you start the channel (but currently that feature is not available in iOS).

After the channel is created, only people invited to the channel even know it exists, and can search its available archives and invite other people. Leaving a private channel blocks your future access—you have to be re-invited to get back in.

Because people who you’ve invited to your channel may not notice it right away, unless you’ve already coordinated with them, you either message them privately or write a message with an @channel @mention in the newly created channel to make sure they’re aware of it. The @channel message will show up as a notification for any channel members who have that sort of notification enabled.

Invite Others to a Private Channel

Nothing prevents a full team member in a private channel from inviting others—the mechanism is exactly the same as for public channels, described just above in Invite Others to a Public Channel. However, each time a new person is invited, the member issuing the invitation is first offered a choice about allowing access to the channel’s message history (Figure 98). (In the mobile apps, you get this prompt even if you’re the only member and have just created the channel.)

**Figure 98:** When inviting new people to a private channel, you have a choice between making its archives available and starting fresh.
Figure 98: When inviting new people to a private channel, you have a choice between making its archives available and starting fresh.

If you agree, the previous message history is available to the new participant or participants, and the channel persists with all the same parameters.

Disagree with that prompt and Slack archives the channel, makes a link visible to the original participants, creates a new channel with the same name and member list as the original, and adds the just-invited person.

Interact in a Channel

Regardless of whether a channel is private or public, you have a number of ways to interact with it, including setting (and reading) its purpose and topic, “pinning” messages for later perusal, and broadcasting announcements. You can also Leave a Channel and Archive a Channel.

Set the Purpose

A channel’s purpose is the general description or goal of the channel. You can set the purpose for a channel when it’s created in the desktop or Web apps, and anyone can edit it in any app.

To see a channel’s purpose:

**Figure 99:** The purpose helps people browsing the channel directory decide if they want to join a channel.
Figure 99: The purpose helps people browsing the channel directory decide if they want to join a channel.

To set the purpose:

**Figure 100:** Open the Channel Details pane to set the channel purpose.
Figure 100: Open the Channel Details pane to set the channel purpose.

Set a Topic

A channel’s purpose, covered just above, is about the overall goal for the channel, whereas the topic is more what you want to focus on for a particular day. It can be a mood, idea, or joke—it should be brief, as it typically appears where just a few words can be shown.

In the desktop and Web apps, the topic appears at the top of the message list underneath the channel name (Figure 101); in the mobile apps, at the top of the message list, tap the channel’s name to open the Channel Settings view. The topic shows up at the top.

**Figure 101:** Look under the channel name to find the channel’s topic.
Figure 101: Look under the channel name to find the channel’s topic.

To set the topic:

**Figure 102:** Tap and type to set the topic in Slack’s iOS app.
Figure 102: Tap and type to set the topic in Slack’s iOS app.

Pin Messages

Sometimes you want to attach a message to a channel or conversation so that you and others can refer to it later. Slack calls this pinning, and at the moment it’s supported only in the desktop and Web apps.

Click the Message Actions button as you hover over any message, and choose Pin to #channel-name (or Pin to This Conversation). You’re prompted to confirm pinning, which seems like overkill, since the consequences of pinning are slight (Figure 103).

**Figure 103:** Pin a message for channel reference.
Figure 103: Pin a message for channel reference.

To see pinned messages, click the Channel Details button on the toolbar to open the Channel Details pane and then expand the Pinned Item section (Figure 104).

**Figure 104:** Pinned messages appear in Channel Info.
Figure 104: Pinned messages appear in Channel Info.

You can remove a pinned message by clicking its hover-over x in the Pinned Item section, or finding the original message and choosing Unpin from #channel-name (or This Conversation) in the Message Actions menu.

Make Announcements in a Channel

Sometimes you need to shout and be heard by everyone! For channel-wide announcements, Slack provides three special account names:

Although those announcement handles alert everyone by default, Slack lets each team member determine how they receive alerts in the desktop, Web, and mobile Slack apps, either by channel or time of day (see Control Slack Notifications). So while each of these special handles ostensibly notifies everyone who meets the given parameters, not everyone may receive the notification right away. Slack also warns you when you try to use an announcement that would affect a lot of people, especially across time zones.

With paid teams, an administrator or user (if an admin allows it) can create and populate user groups that act like @channel for the members assigned to each group. So a company might have a group called @marketing, and using that handle in a message would notify all the members of that group.

If you have permission to manage groups, you can make changes in the desktop and Web apps by clicking the More Items button in the toolbar, choosing Team Directory, and selecting the Groups tab. On the tab, click Edit User Groups or Add a New User Group.

Think carefully about how you use each of these handles. You can wind up pinging a whole lot of smartphones and computers, and thus cause people to become sufficiently annoyed with you—or with Slack in general—that they end up interacting with the team much less.

Leave a Channel

You (and others) are free to leave any channel except for #general at any time—the door’s not locked. Just head on out:

You can’t sneak out, however. When you do this, a message about your departure appears in the channel.

Regular users can rejoin a channel at any time. A guest in a paid team has to be invited again to rejoin a channel. Members of private channels must be re-invited.

Archive a Channel

You may need a channel only for a period of time, or you may want to retire it temporarily. The Archive option lets any full member remove a channel from active use without deleting its messages:

An archived channel can’t be selected or used for messaging, but archived messages do appear in Slack search results and they can be browsed (and de-archived) in the Message Archives. Skip back to Use the Message Archives for help with accessing this part of your Slack team.