Metadata

This is the base class for all metadata types. You cannot edit this object. A component is an instance of a metadata type.

Metadata is analogous to sObject, which represents all standard objects. Metadata represents all components and fields in Metadata API. Instead of identifying each component with an ID, each custom object or custom field has a unique fullName, which must be distinct from standard object names, as it must be when you create custom objects or custom fields in the Salesforce user interface.