Slack is a popular team communication tool that facilitates collaboration and information sharing within organizations. Its key features include:

1. Channels: Organized spaces for different topics, projects, or teams.
2. Direct Messaging: For private conversations between team members.
3. File Sharing: Easily share documents, images, and other files.
4. Integrations: Connects with various other tools like Google Drive, Trello, and Asana.
5. Searchable History: Find past messages and files quickly.
6. Notifications: Customizable alerts to stay informed without being overwhelmed.

Slack is effective for teams of any size, supporting both real-time and asynchronous communication, thus enhancing productivity and team cohesion.