Slack for Beginners: Channels, Threads and Free Plan Limits

Public and private channels, and the one you cannot leave

Slack's help page defines two channel types. In a public channel, members (not guests) can find, view and join it, and its messages and files show up in search for every workspace member. In a private channel, a current member must add you, and messages show in search only for the people inside.

You pick the type when you create a channel and can convert it later. Every workspace also has a #general channel. Members, but not guests, are added automatically and cannot leave, and #general cannot be archived, deleted or made private.

Threads keep a reply attached to its message

On desktop, hover over a message and click the Reply in thread icon. On mobile, tap the message and choose Reply in Thread. A checkbox under the reply box also posts your answer to the channel, for the times everyone should see it.

Notifications differ by place. In one-to-one DMs you hear about all new thread replies by default. In channels and group DMs you are notified only if you started the thread, replied to it or were mentioned. Find the threads you are part of under Home > Threads. Threads work for all members and guests on every plan.

Shortcuts for Mac and Windows, plus one-key message actions

Slack's shortcut page lists keys for both systems. Some work only in the desktop app, not in a browser, and custom shortcuts are not supported.

• Quick switcher: Cmd + K on Mac, Ctrl + K on Windows (Ctrl + T in the desktop app).
• Threads view: Cmd + Shift + T or Ctrl + Shift + T.
• Activity view: Cmd + Shift + M or Ctrl + Shift + M.
• Browse channels: Cmd + Shift + L or Ctrl + Shift + L.
• Start a search: Cmd + G or Ctrl + G. Search the current conversation: Cmd + F or Ctrl + F.
• Jump to the latest unread: Cmd + J or Ctrl + J. All unreads: Cmd + Shift + A or Ctrl + Shift + A.
• New message: Cmd + N or Ctrl + N. Set status: Cmd + Shift + Y or Ctrl + Shift + Y.
• On a focused message: T opens its thread, E edits, P pins, A saves, M sets a reminder, R adds a reaction.

What the Free plan really limits

Slack's pricing page says free messages are saved and searchable for 90 days, with up to 10 app integrations and one-to-one huddles only. Pro and higher plans list unlimited history and integrations, and group huddles.

The help page on free-version limits adds a harsher rule: messages and files more than one year old are deleted, and from August 26, 2024 that applies to free workspaces. Slack counts third-party and custom app installations toward the 10, and you must uninstall some to add more.

Prices per user, in euros as shown on 2026-11-01

On the page I read, Pro is 8.25 euros a month with monthly billing or 6.75 with annual billing. Business+ is 18 euros monthly or 15 annually. Enterprise+ is by contacting sales. Slack lists no storage limit for any plan on that page.

There is an offer of 50% off for 3 months on monthly Pro and Business+ plans, shown as 4.13 and 9 euros. The terms say it must be bought within the first 7 days of creating your team and does not apply to annual plans.

A worked example: a 5-person team over one year

A team of 5 on Pro with annual billing pays 5 x 6.75 = 33.75 euros a month, or 405 euros over 12 months. On monthly billing it would be 5 x 8.25 = 41.25 euros a month, or 495 euros over 12 months.

The 90 euro gap is the price of billing monthly. A team that stays on Free pays nothing but loses searchable history older than 90 days, so a decision made in March is gone from search by June.

What happens when you drop back to Free

Slack lists several changes on downgrade. Custom sidebar sections collapse into 3 defaults: Channels, DMs and Starred. Canvases and Lists become read-only. Workflows stop working, user groups are emptied, guest accounts are deactivated, and Slack Connect channels disconnect.

Paid-only features that disappear include channel email addresses, custom message retention, detailed analytics, and AI features such as summaries and huddle notes. Read this list before cancelling.

Inviting people: 30 days and 400 uses

An invitation stays active for 30 days after you send it, and owners and admins can resend a pending one. An invite link is also active for 30 days and can be used by up to 400 people. Slack says limits can apply if many invitations go unaccepted, and revoking pending invites does not lift a limit.

Mistakes new users make

Posting everything in #general buries it, since nobody can leave that channel. Replying in the main channel instead of a thread splits a conversation across screens. Choosing a private channel by default hides messages from search, while Slack's own advice is to use public channels when possible and give each one a clear topic and description.

I could not find an official message length limit or huddle size limits, so none are stated. If a Slack error is on your screen and you cannot parse it, Crade can read the screen and explain it.

Who Slack suits

Slack suits teams of 2 or more who want questions answered in minutes and kept searchable. Solo users, or groups that only need a once-a-week update, may find email enough. Groups that need records beyond 90 days should price Pro before starting on Free.