In Slack, team members can send and receive all types of information and mention specific people to ensure that they see the conversation. Slack can also sync with Dropbox, Google Drive, and Trello, making it even easier to transfer and access files that have been stored in the cloud. This way, you can share information without having to switch applications.
Slack is also compatible with JIRA and other tools for statistics, plus video calls on Hangouts. There is no limit to the number of users, so no matter how big your company, everyone can keep in touch at all times with this private chat.
It only allows you to see the last 10,000 messages in the history.