As of September 5 2009, anyone who wants to register an internet domain for the Bulgarian top domain level of .bg, can do so in Cyrillic.

The country's top domain level registrar Register.bg said it had opened registration for internet addresses in Cyrilic, using Internationalized Domain Names (IDN).

Since the beginning of the internet, domain names could only be written in a small set of Latin characters, using only letters, numbers and hyphens. Leters could be capitalized, but could not have accents. With the wider use of the internet from the 1990s on, especially outside North America and Western Europe, efforts have been under way to make it possible to write internet addresses in other alphabets without breaking the existing addressing structure.

The way IDN works is by converting any internet address that contains at least one non-standard character, into either ASCII or Unicode - both of which can be processed by the existing Domain Name Address system.

Because of this, domains that are to be registered in Cyrillic need to have at least one letter that is different from those that exist in the Latin alphabet; б, г, д, ж, и, й, л, п, ф, ц, ч, ш, щ, ь, ъ, ю or я.

During the first three months of registrations, all applications for the registration of a .bg domain in Cyrillic will be added to a waiting list. After December 4, the registration for all domains for which only one registrant has applied will be finalized, Register.bg said.