Slack is a tool for managing team communications. Slack brings together all of a team's messages, files, and posts from Twitter, Dropbox, Trello, Google Docs, GitHub, and other services in one place. Once collected, these materials are archived and indexed so that they can all be searched at once. Native applications are available for iOS and Android devices to give users full access to Slack on the go.
Slack comes with an API that allows users to integrate it with other third-party applications. Some out-of-the-box integrations are provided, but the API provides additional functions above and beyond those. With the Slack API, users can upload an image or file, get a channel's history, set a channel's "unread" marker, retrieve lists of files, and search a Slack instance.