Standard schematic libraries allow you to attach PCB footprint models to components. Usually, each model link references a file (PCB library file) somewhere outside of the schematic library. So the schematic library saves a link, that is, instructions on where to find the model you attach.
Periodically, CircuitStudio will need to locate these models - when you run a board update, for example, the linking instructions will be followed for all current footprints in your design. The search sequence for matching models starts with libraries in the current project, installed PCB libraries, then any files found on the project search path. The management of these separate source libraries is left entirely in your hands, meaning that CircuitStudio cannot offer any guarantees that your models will find matches. These links in schematic libraries are brittle, and easily broken by everyday management tasks such as renaming folders on a hard drive, or reassigning labels to a central server.
CircuitStudio has a solution - the Integrated Library. The integrated library includes not only the schematic library (or libraries), it also has all the associated model libraries bundled in. If a component came from an integrated library, CircuitStudio is guaranteed to find the right model if it can simply locate the integrated library it came from.
Because the components and models are entirely contained within a single .IntLib file, these libraries offer portability to designers who divide their work among different workstations, or who want to share their designs with others. Simply installing the same, single file in the Libraries panel of any PC running CircuitStudio will mean that component-to-model links will remain secure (assuming, again, that components were placed in the design from that integrated library).
These libraries are also checked for integrity when they are compiled. That means they are not only checked for availability, but for correct pin mappings. Even designers who want to stay with discrete library files should compile their schematics in an integrated library package, if only to ensure that the source components will map correctly to the target models. Once satisfied, they can ignore the integrated library they created, and keep placing directly from their schematic libraries.