What is a reserved domain name?
Reserved domain names are domain names withheld by the central registry, making them unavailable for general registration.
The reasons for reserving domains vary. Some are held back to avoid "name collisions," while others, like one- and two-character domains, may be restricted by the registry’s decision. Registries also reserve certain valuable or premium domains. For instance, the .ME registry reserves premium names that require an application to register.
Occasionally, registries release previously reserved domains, often labeling them as premium and selling them at higher prices.