Slack

Slack is a program for collaboration within companies. Employees write messages to each other in it, similar to a messenger app on a phone. The most important difference from WhatsApp: conversations are not sorted by person, but by topic. Every project, every department, or every question has its own group chat, called a “channel” in the program. Anyone new to the team can read up on what was discussed before. Slack was released in 2013 and has belonged to the US software company Salesforce since 2021, which paid around 27 billion dollars for it.

How Slack displaced email

Before Slack, communication in offices ran mainly through email. That has one practical disadvantage: information sits in private inboxes. Anyone not on the distribution list learns nothing, and later can’t find anything either. In an open channel, it’s different. Everything written remains visible and searchable for the whole team.

It is precisely this stockpile of conversations that makes Slack interesting for business news. A company’s messages contain its knowledge: decisions, justifications, customer problems. Anyone who sets an AI on this can evaluate that knowledge. That’s why Slack is considered a particularly valuable building block within the Salesforce group, and not just a chat app.

The distinction from Microsoft Teams is important. Teams can do similar things and is usually already included in Microsoft’s office suite. The competition between the two is a perennial topic in the tech industry. Slack even filed a complaint against Microsoft with the EU Commission because Teams was bundled and sold alongside other products.

Channels, threads, and connected programs

A company sets up its own area in Slack, the workspace. The channels are located within it. Some are open to everyone, others only to selected people. Replies to a message can be bundled into a “thread,” i.e., an indented sub-strand. This way, several conversations in the same channel don’t get mixed up.

The more technically interesting part is the connections to other programs. Slack offers interfaces through which outside software is allowed to send messages. An interface is a defined request format that programs use to talk to each other. For example, a server automatically reports to a channel when a website goes down.

Such automatic writers are called bots. A bot can also respond to commands, for instance registering vacation time or creating a ticket. Since 2024, Slack has additionally been building in language models, i.e., AI systems that understand and formulate text. They summarize long channels or answer questions from the conversation history. The corresponding product is called Slack AI and costs extra.

Slack in school, companies, and stock market news

Slack is encountered most often in professional life, especially in software companies, start-ups, and editorial offices. Universities, associations, and open-source projects also use it. For private individuals it is atypical, since it is tailored to teams. There is a free version, but it only shows more recent message history.

The name appears in business news for two reasons. First, as an example of how corporations build AI into existing software instead of launching their own chatbots. Second, in disputes over data protection: in 2024 there was criticism because Slack had used customer data to train its own features.

A common misconception is that Slack itself is an AI. It is first and foremost a communication tool. The AI sits on top and works with the texts that people leave there. If no one at a company writes clearly, even the best summary won’t help.