.OLB File Extension

Object library that contains data types and constants referenced by MS Office components; may cause certain Microsoft programs to not function correctly if moved or renamed.

OLB files are also referred to as Office Object Library files.

CAD file used by OrCAD, a program used for designing printed circuit boards (PCBs); saves "symbols," which are the electric circuit components that can be put together to construct a PCB design; often used as a library for defining virtual circuit components that match the specifications of real-world circuit components.

OLB files are often included as part of an OrCAD project (.OPJ file).