IMS is often referred to as IMS/DB or IMS/DC, depending on the specific functionality being used:

IMS/DB (IMS Database) : IMS/DB is the component of IMS that provides hierarchical database management capabilities. It allows organizations to organize, store, and retrieve data in a hierarchical format. IMS/DB databases consist of segments organized in a tree-like structure, with parent-child relationships defining the hierarchy. IMS/DB is widely used in industries such as banking, finance, telecommunications, and healthcare for managing mission-critical data and supporting transaction processing applications.

IMS/DC (IMS Data Communications) : IMS/DC is the component of IMS that provides data communications and transaction processing capabilities. It enables online transaction processing (OLTP) by facilitating communication between terminals or other online devices and the IMS system. IMS/DC supports features such as transaction routing, message queuing, and terminal input/output processing. It is used to develop and deploy online applications that interact with IMS databases in real-time.

Combined, IMS/DB and IMS/DC provide a comprehensive platform for developing and running large-scale transaction processing applications in mainframe environments. IMS is known for its scalability, reliability, and performance, making it a popular choice for organizations with demanding OLTP requirements.