BizTalk enables companies to automate business processes, through the use of adapters which are tailored to communicate with different software systems used in an enterprise. It provides enterprise application integration, business process automation, business-to-business communication, message broker and business activity monitoring.
BizTalk provides a powerful development and execution environment that integrates loosely coupled, long-running business processes, both within and between businesses. It handles transactions that run as long as weeks or months, not just minutes or hours.
Microsoft's offers two flavours of BizTalk - BizTalk Server for on-premises integration and Microsoft Azure BizTalk Services for integration hosted in the cloud.