Slack is a messaging software designed for users who would like to streamline their communications on a single platform. Designed with businesses in mind, Slack's instant messaging software allows teams to organize conversations in specific groups (i.e. by project, team, or topic). Users are invited to join conversations through a specific URL or via invitation sent by a team administrator. All content shared within a conversation (such as files, keywords, and individual users) is completely searchable, making it easier than ever to keep track of how a conversation progresses.
Slack is available in both free and paid versions, depending on a team's needs. Its free version only includes basic features such as two-person calls, 10 app integrations, and 5 GB of storage.