A TP monitor for Windows NT servers from Microsoft that supports transaction-based applications on LANs, the Internet and intranets. It also serves as the infrastructure for a multi-tier system. It is used in the middle tier between the client and the database server. Microsoft Transaction Server (MTS) supports two-phase commit with its included Distributed Transaction Coordinator (DTC). Based on Microsoft's component software architecture (COM), MTS hosts business logic written as ActiveX Server Components. A component is written for a single user, and MTS scales the process for many users. The server components access the required data via any of several interfaces including ADO, OLE DB and ODBC. In Windows 2000, MTS is not a separate component, but is part of the operating system. See Microsoft Message Queue Server.