Slack is a team collaboration tool that enables the members to communicate with each other. Team conversations can be organized via private channels or just channels. Team conversations can easily be organized in open channels where you want each member to have a transparent view of what's going on within a team, project, or topic, or even anything under the sun.
On the other hand, private channels are useful especially when it comes to handling and sending out sensitive information. Creation of private channels can be customized only for designated team members and nobody else can join or see your private channels.
If you want to reach a colleague right away, then send him or her a direct message which is also secure and private.
Slack is not just a simple messaging app for teams, you can also drag and drop spreadsheets, documents, PDFs, images, and any other files into slack to be shared to designated team mebers.
If you are tired of opening and jumping from one app to another, you can easily connect all other tools you use with slack. That way, you integrate all apps you use and be notified within slack like sales leads, error logs, code check-ins, support requests and many more. And lastly, with slack, you can easily search your archives from files to conversations.