The System Landscape Directory of SAP NetWeaver (SLD) serves as a central information repository for your system landscape. A system landscape consists of a number of hardware and software components that depend on each other with regard to installation, software updates, and demands on interfaces
SLD stores information about the all the component installed in the landscape. It stores information based on CIM.Learn more about CIM.
SAP Process Integration (PI) uses the SLD to store information about business systems, which are logically connected to technical systems