A type library (.tlb) is a binary file that stores information about a COM or DCOM object's properties and methods in a form that is accessible to other applications at runtime. Using a type library, an application or browser can determine which interfaces an object supports, and invoke an object's interface methods. This can occur even if the object and client applications were written in different programming languages. The COM/DCOM run-time environment can also use a type library to provide automatic cross-apartment, cross-process, and cross-machine marshaling for interfaces described in type libraries.