A metadata token is an implementation-dependent encoding mechanism. Partition II describes the manner in which metadata tokens are embedded in various sections of a CLI PE/COFF module. Metadata tokens are embedded in CIL and native code to encode method invocations and field accesses at call sites; the token is used by various infrastructure services to retrieve information from metadata about the reference and the type on which it was scoped in order to resolve the reference.
A metadata token is a typed identifier of a metadata object (such as type declaration and member declaration). Given a token, its type can be determined and it is possible to retrieve the specific metadata attributes for that metadata object. However, a metadata token is not a persistent identifier. Rather it is scoped to a specific metadata binary. A metadata token is represented as an index into a metadata data structure, so access is fast and direct.