Donuts is an Internet domain name registry founded in 2011 by Paul Stahura and three other co-founders. They are backed by institutional capital such as Austin Ventures, Generation Partners and has raised more than $100M in its A financing round. They also applied at ICANN for 307 top-level-domain names (sometimes called TLDs or extensions) in 2012.
As Donuts is required by ICANN to only sell domains via registrars such as Godaddy, 1&1.com, eNom and many others, their target market are varied as they cannot control who their target audience may be. However, this is not necessary a bad thing as this has helped them to offer services to both B2C and B2B consumers on a larger scale by piggy-backing on these registrars. Based on the latest domain release of .CITY and .HEALTHCARE, it appears that they are growing to service a bigger market potentially in the government and health sector.
In addition, Donuts offer varied identities in multiple languages and character sets in organizations worldwide (topping 2 million registrations) which suggests that they are gaining popularity within an existing market who now gets to enjoy more choices in specific domains that cater better to their needs.