Slack
Also known as: Slack workspace, Slack channel, team messaging
Slack is a business communication platform built around channels: dedicated spaces for teams, projects, or topics.
Messages, files, and discussions live in searchable channels rather than scattered across email threads. Slack supports direct messages, voice calls (Huddles), and integrations with hundreds of tools. It's particularly popular with tech companies and startups and is available as a desktop, web, and mobile app.
Slack, explained at three levels
At home
Slack is a messaging app for teams, a bit like a group chat but more organized. Instead of one big group chat, Slack has channels, like #general for company-wide announcements, #marketing for the marketing team, and #random for non-work chat. You can also send direct messages to individuals. Everything is searchable, so finding an old conversation takes seconds.
At work
At work, Slack replaces a lot of internal email. Quick questions, project updates, file sharing, and team announcements happen in Slack channels instead of long email threads. You get notifications when you're mentioned with @yourname and can set your status to 'In a meeting' or 'Focusing' to let colleagues know your availability.
At home
Slack threads keep channels tidy: instead of replying directly in a channel (which clutters everyone's view), you reply in a thread attached to the original message. Only people who've joined the thread get notified of new replies. Huddles allow instant voice conversations: click a button and you're in a live audio call with your channel members.
At work
Slack integrates with most SaaS tools in the business software stack. GitHub sends pull request notifications to a #dev channel. Jira posts ticket updates. PagerDuty sends incident alerts. These integrations mean your team gets relevant information in context without manually checking multiple dashboards. Workflow Builder (no code required) automates processes like daily standups, onboarding checklists, and approval requests.
At home
Slack stores every message on its servers and indexes it for search, which is why history is searchable from any device. On the free plan, only the last 90 days of messages and files stay visible. Notifications are rule-driven: channel settings, keywords, mentions and quiet hours decide what reaches you. Integrations post through bots and webhooks that write into channels like any other member. In my view, careful notification settings matter more than any shortcut, because Slack fails when it becomes constant noise.
At work
Slack's API allows organizations to build custom bots that automate workflows, post scheduled reports, or create interactive approval flows using Block Kit (Slack's UI component system). At enterprise scale, Slack Enterprise Grid provides centralized administration across multiple Slack workspaces in a single organization with shared channels between them. Data retention policies, DLP integrations, and eDiscovery exports are available on Enterprise plans.
Real-world examples
At home
Aisha joined a volunteer-run arts collective that used Slack. There was a #events channel for upcoming shows, a #volunteers channel for logistics, and a #photos channel where people shared pictures. She turned on notifications only for direct messages and found it much less overwhelming than an email list.
At work
Fatima's engineering team used Slack with a #deploys channel connected to their CI/CD pipeline. Every time a deployment finished, Slack automatically posted whether it succeeded or failed, with a link to the build log. Engineers didn't need to check a separate dashboard: relevant information came to them.
How it compares
| feature | Slack | Microsoft Teams | Discord |
|---|---|---|---|
| Primary use | Team messaging and collaboration | Meetings plus messaging (Microsoft 365) | Community and voice-first chat |
| Integration ecosystem | 2,600+ app integrations | Deep Microsoft 365 integration | Gaming, bots, limited business apps |
| Video and audio calls | Huddles (audio), basic video | Enterprise-grade meetings | Voice channels, video calls |
| Channel organization | Flat list plus sections | Teams > Channels hierarchy | Servers > Categories > Channels |
| Best for | Tech teams, startups, integrations | Microsoft 365 organizations | Communities, gaming, informal teams |
Slack is the best choice for teams that want a wide integration ecosystem and channel-based messaging as their primary communication mode. Microsoft Teams is better for organizations deeply embedded in Microsoft 365 who need enterprise-grade video meetings and document collaboration. Discord suits communities and informal teams but lacks enterprise management features.
For analysts
When implementing Slack, channel governance is critical. Without a naming convention and channel purpose policy, organizations quickly accumulate hundreds of channels with overlapping purposes and low signal-to-noise ratios. A channel audit and cleanup, often needed 12-18 months after adoption, is a predictable maturity milestone.
History & origin
Slack launched in August 2013, created by Stewart Butterfield and the team at Tiny Speck as an internal communication tool for their online game Glitch. The game failed but the internal tool was so useful they pivoted to launching it as a product. Slack grew faster than almost any business software of its era, passing 10 million daily active users in 2019, the year it went public. Salesforce acquired Slack for $27.7 billion in 2021. Slack's channel-based model influenced how teams think about asynchronous communication and sparked the modern wave of team chat tools.