Curation Identity Service
A fundamental requirement for a digital library is to distinguish one object from all others. This is done through identifiers.
An identifier is an association between a character string and an object. Objects can be a file or group of files, parts of files, persons, organizations, abstractions, etc. Identifiers are created through a process called "minting." The association between the identifier and the object it identifies is called "binding." And the process by which a URL with this identifier points to the correct object is called "resolution." 
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ARK: Archival Resource Key (Specification)
An ARK is a URL created to allow persistent, long-term access to information objects. An ARK contains parts that are impervious to such changes and parts that are flexible enough to support technological changes/improvements. The idea is to create a stable "name" or reference that can be permanently associated with that specific object. More ...
NOID: Nice Opaque IDentifier (Software)
The NOID software tool mints (generates) opaque identifiers and tracks information to help them remain unique, stable, and closely connected to the objects they identify. These identifiers should be opaque enough to age and travel well, but should easily resolve (connect you) to objects and to their descriptions.
Identifiers minted by NOID have long-term and short-term uses. For example, NOID can mint transaction identifiers and short-term web session keys. A more visible use of NOID is to mint identifiers for the purpose of creating long-term persistent object names (e.g., ARKs, Handles); embedded inside a URL, such an identifier can provide object access when entered into a web browser.
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N2T: Name-to-Thing Resolver (Consortium)
N2T (Name-to-Thing) is a persistent identifier resolver and a consortium of cultural memory organizations. The consortium has no fees or requirements, and merely offers its members the option to publicize a protected form of their URLs supported by the resolver.
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